0:00:13 > 0:00:17This is a British mathematician called Bill Tutte.
0:00:17 > 0:00:19You won't have heard of him.
0:00:19 > 0:00:22But in 1943, he pulled off what many believe
0:00:22 > 0:00:26was the greatest intellectual feat of World War Two.
0:00:26 > 0:00:30It shortened the war and saved millions of lives.
0:00:30 > 0:00:33He died in 2002 without ever being officially recognised
0:00:33 > 0:00:34for his achievement.
0:00:36 > 0:00:39This is a former GPO engineer called Tommy Flowers.
0:00:39 > 0:00:43In 1944, he turned Tutte's mathematical ideas
0:00:43 > 0:00:46into the world's first computer.
0:00:46 > 0:00:48He died in 1998.
0:00:48 > 0:00:52Chances are, you won't have heard of him either.
0:00:52 > 0:00:55Backed by the brightest talents of Bletchley Park,
0:00:55 > 0:00:58they allowed Britain to break a top secret machine
0:00:58 > 0:01:01employed by Hitler to dictate the course of the war.
0:01:01 > 0:01:03This machine was NOT Enigma.
0:01:03 > 0:01:06It was something far more secret and significant...
0:01:06 > 0:01:09and you definitely won't have heard of that.
0:01:09 > 0:01:11It was Hitler's Blackberry really.
0:01:11 > 0:01:17That intelligence probably shortened the war by a couple of years.
0:01:17 > 0:01:21They were the forgotten heroes of Bletchley Park.
0:01:21 > 0:01:26This is the story of a secret war and how two men changed the world
0:01:26 > 0:01:28and then disappeared from history.
0:01:49 > 0:01:51This is Bletchley Park.
0:01:51 > 0:01:55In 1939, it became the wartime headquarters of MI6.
0:02:00 > 0:02:03If you know anything about what happened here,
0:02:03 > 0:02:06it will be that a man called Alan Turing
0:02:06 > 0:02:10broke the German naval code known as Enigma and saved the nation.
0:02:11 > 0:02:15And he did... but that's only half the story.
0:02:17 > 0:02:20There were three heroes of Bletchley Park.
0:02:20 > 0:02:22The first is Alan Turing.
0:02:22 > 0:02:28The second was Bill Tutte who broke the Tunny system,
0:02:28 > 0:02:30a quite amazing feat.
0:02:30 > 0:02:33And the third was Tommy Flowers,
0:02:33 > 0:02:38who, with no guidelines, built the first computer ever.
0:02:39 > 0:02:43Amazingly, the story of Tutte and Flowers has never been fully told -
0:02:43 > 0:02:47but then again, Bletchley is Britain's fortress of secrets.
0:02:47 > 0:02:49The secrecy about Tunny and Colossus
0:02:49 > 0:02:53has completely distorted the history of computing
0:02:53 > 0:02:56and it's also left the story
0:02:56 > 0:02:59of the World War Two codebreaking effort incomplete.
0:02:59 > 0:03:02It's like there's not enough room on the stage
0:03:02 > 0:03:05because the Enigma story has taken up so much space.
0:03:23 > 0:03:25It's not surprising that there are stories
0:03:25 > 0:03:28still to be told about this place.
0:03:30 > 0:03:33Bletchley Park was Churchill's house of secrets.
0:03:33 > 0:03:37It didn't even appear on any map.
0:03:37 > 0:03:40Nicknamed "Station X", this sprawling complex was home
0:03:40 > 0:03:43to a clandestine army engaged in a shadowy struggle
0:03:43 > 0:03:45for military intelligence.
0:03:53 > 0:03:57Bletchley Park's codebreaking history began in 1939,
0:03:57 > 0:04:01with a tiny attic radio station hidden at the top of the house.
0:04:01 > 0:04:05It would eventually give its name to the entire estate.
0:04:05 > 0:04:06Station X.
0:04:19 > 0:04:24As the war progressed, operations expanded out from the main house
0:04:24 > 0:04:27to a haphazard collection of huts and concrete blocks.
0:04:27 > 0:04:30Here, some of the most brilliant minds in the country
0:04:30 > 0:04:34were involved in a constant battle to learn the enemy's secrets.
0:04:39 > 0:04:42Arguably, the toughest and most rewarding struggle
0:04:42 > 0:04:44was against a code called "Tunny".
0:04:44 > 0:04:47In defeating it, Bill Tutte and Tommy Flowers
0:04:47 > 0:04:49would change the world.
0:04:51 > 0:04:54Captain Jerry Roberts worked alongside Bill
0:04:54 > 0:04:56and was involved in the attack on Tunny.
0:04:56 > 0:05:00He is the last surviving codebreaker from an elite group
0:05:00 > 0:05:02known as "The Testery".
0:05:02 > 0:05:06Now aged 90, this is the first time he has visited this part of the Park
0:05:06 > 0:05:08since the war.
0:05:08 > 0:05:10General Eisenhower said Tunny decrypts
0:05:10 > 0:05:13shortened the war by at least two years.
0:05:15 > 0:05:19In its heyday, the place was really buzzing.
0:05:19 > 0:05:22Thousands of people working here, hard.
0:05:37 > 0:05:40Very disappointing to see it in this shape.
0:05:44 > 0:05:47The Testery were backed by a huge team of people
0:05:47 > 0:05:51processing the information gained from the broken codes.
0:05:51 > 0:05:54And while much of Bletchley has been restored,
0:05:54 > 0:05:57the places that housed those workers are abandoned.
0:05:57 > 0:06:01The secrets they uncovered, though, are still coming to light.
0:06:16 > 0:06:19World War Two was a conflict uniquely designed
0:06:19 > 0:06:22to create secret messages and exploit them.
0:06:22 > 0:06:26The rapidity and mobility of armies during the Second World War
0:06:26 > 0:06:29meant that you couldn't get your fixed-line communications,
0:06:29 > 0:06:32which are much more secure, up quickly enough.
0:06:32 > 0:06:37So increasingly, they came to rely upon radio technology
0:06:37 > 0:06:40and radio technology, of course, is broadcast to the world
0:06:40 > 0:06:43and they would, therefore, be able to intercept it.
0:06:43 > 0:06:44It's a considerable weakness.
0:06:45 > 0:06:48If you could break into the right encoding system
0:06:48 > 0:06:51then you could deliver victory.
0:06:51 > 0:06:54That was what Bletchley was built to do and their most secret
0:06:54 > 0:06:58and stunning success came against a code which they nicknamed "Tunny"
0:06:58 > 0:07:01and the Germans called "Lorenz".
0:07:07 > 0:07:10Its existence was a tightly guarded secret.
0:07:10 > 0:07:13Even now it's not common knowledge.
0:07:13 > 0:07:15Tunny was generated by a new top-secret machine,
0:07:15 > 0:07:18a device Hitler called his "Geheimschreiber" -
0:07:18 > 0:07:20"The secrets writer".
0:07:20 > 0:07:24To understand its genesis and the need for this super code,
0:07:24 > 0:07:27you first have to look at the system that preceded it.
0:07:27 > 0:07:28Enigma.
0:07:34 > 0:07:37Enigma would dominate the early work of the codebreakers
0:07:37 > 0:07:40of Bletchley Park, and it was a formidable opponent.
0:07:41 > 0:07:46Well, this is an Enigma machine, a type of cipher machine
0:07:46 > 0:07:49that was used throughout the Second World War by the Germans.
0:07:49 > 0:07:52Throughout the Second World War, they believed that the ciphers
0:07:52 > 0:07:55that were made on this machine could not be broken.
0:07:55 > 0:08:00If I press the key for letter "N", lamp "W" lights up on this occasion.
0:08:00 > 0:08:02So "N" would be enciphered into "W".
0:08:02 > 0:08:07If I release my finger and press "N" a second time, on this occasion,
0:08:07 > 0:08:10lamp "M" lights up, and the reason for that
0:08:10 > 0:08:12is the rotors at the back of the machine have moved
0:08:12 > 0:08:17each time I press a key and that changes the internal wiring.
0:08:19 > 0:08:22Enigma masked Germany's wireless traffic.
0:08:22 > 0:08:26The Morse code transmissions that were monitored back in Britain by "Y Stations",
0:08:26 > 0:08:28monitoring and recording stations,
0:08:28 > 0:08:31operated almost exclusively by women.
0:08:31 > 0:08:34From the First World War, there was considerable emphasis put on
0:08:34 > 0:08:38the quality of wireless receivers.
0:08:38 > 0:08:41You might think that the most important thing in wireless
0:08:41 > 0:08:45is the transmitter or the medium, the ether through which messages travel,
0:08:45 > 0:08:46but for the cryptographers,
0:08:46 > 0:08:49the main thing was the quality of the receiver,
0:08:49 > 0:08:52being able to pick up the last lingering trace of a message,
0:08:52 > 0:08:56and that was where the British radio engineers
0:08:56 > 0:08:59were considerably more advanced than their German counterparts,
0:08:59 > 0:09:02and the Germans simply didn't believe that their messages
0:09:02 > 0:09:05could be picked up as far away as they were.
0:09:05 > 0:09:08They didn't believe that messages from Russia, for example,
0:09:08 > 0:09:10could be picked up in Britain.
0:09:12 > 0:09:15For the first years of the war those listening posts
0:09:15 > 0:09:17were dedicated to picking up Enigma traffic.
0:09:17 > 0:09:21Then, in 1941, a new and strange sound
0:09:21 > 0:09:24began to be picked out from the ether.
0:09:27 > 0:09:30"A new kind of music", it was described as
0:09:30 > 0:09:33by the British listeners when they first heard it.
0:09:35 > 0:09:39This strange music was a new coding machine delivering messages
0:09:39 > 0:09:42not by Morse, but by teleprinter.
0:09:47 > 0:09:51The information war was about to move into new territory.
0:10:04 > 0:10:07The advent of machine-made codes had one immediate effect
0:10:07 > 0:10:09on Bletchley Park -
0:10:09 > 0:10:12they began to recruit mathematicians.
0:10:12 > 0:10:17Mathematicians were regarded as weird, incomprehensible people
0:10:17 > 0:10:20and it just wasn't really understood what contribution
0:10:20 > 0:10:22they could make to code-breaking.
0:10:22 > 0:10:27These machine ciphers that were introduced, Enigma and so on,
0:10:27 > 0:10:29and there were others as well,
0:10:29 > 0:10:32are incredibly complex mathematically.
0:10:32 > 0:10:33I mean, the First World War,
0:10:33 > 0:10:36the British code-breakers were wordsmiths,
0:10:36 > 0:10:39people who translated ancient documents for example,
0:10:39 > 0:10:41cos it was all about words,
0:10:41 > 0:10:44but in the Second World War it was much more about mathematics.
0:10:44 > 0:10:47The mathematicians were thrown into the front line
0:10:47 > 0:10:49against this new mystery system.
0:10:49 > 0:10:53Even though the Nazis believed Enigma was unbreakable,
0:10:53 > 0:10:55Hitler demanded more security.
0:10:59 > 0:11:02His style of command called for a new and more direct
0:11:02 > 0:11:07communications network. It would carry more information
0:11:07 > 0:11:11and supersede the tangle of Morse traffic which his forces generated.
0:11:11 > 0:11:13Enigma was really out of date technology
0:11:13 > 0:11:15by the time the war started.
0:11:15 > 0:11:17Three operators were required
0:11:17 > 0:11:20and then another three operators at the receiving end.
0:11:20 > 0:11:24There'd be the guy who actually typed the message,
0:11:24 > 0:11:29the operator would have an assistant who would painstakingly note down
0:11:29 > 0:11:31the letters as they lit up,
0:11:31 > 0:11:34and then that would be handed over to a radio operator
0:11:34 > 0:11:38who would translate that into the "dit-dit-da" of Morse code.
0:11:38 > 0:11:40BEEPING
0:11:40 > 0:11:42And then the process was reversed at the other end.
0:11:42 > 0:11:45So you had six people co-operating in the transmission
0:11:45 > 0:11:48of a single message with Enigma. Very slow, very clumsy.
0:11:48 > 0:11:53So the vast volumes of information needed to fight a modern war
0:11:53 > 0:11:58at that time would simply have overwhelmed a system
0:11:58 > 0:12:01based upon using an Enigma machine, so they needed something which would
0:12:01 > 0:12:04cope with the throughput of information required.
0:12:07 > 0:12:11And this is it. The machine Hitler had dreamed of.
0:12:11 > 0:12:14The Lorenz SZ40.
0:12:14 > 0:12:16Or as the Allies called it, "Tunny".
0:12:19 > 0:12:22This is an example, quite a rare example,
0:12:22 > 0:12:25of what is called a Lorenz enciphering attachment.
0:12:25 > 0:12:28Quite a complicated machine.
0:12:28 > 0:12:31If I lift up the cover and show you the interior.
0:12:31 > 0:12:36If you count up, you'll find that this device has got 12 wheels in it.
0:12:36 > 0:12:40The Lorenz was much more sophisticated than Enigma.
0:12:40 > 0:12:43The operator at one end typed in plaintext
0:12:43 > 0:12:46and the operator at the other end received the plaintext
0:12:46 > 0:12:49on his teleprinter without any intervention on his part.
0:12:51 > 0:12:54The way in which this Lorenz cipher machine worked was it would apply
0:12:54 > 0:12:56two layers, two keys, to your message,
0:12:56 > 0:13:00so it wouldn't encipher it once, it would encipher it twice.
0:13:02 > 0:13:07The first encipher used five wheels.
0:13:07 > 0:13:09Then they would apply a second key
0:13:09 > 0:13:13and this used similar five wheels and they had another two wheels
0:13:13 > 0:13:17that were called, what we called "stutters" in the key.
0:13:17 > 0:13:20And then that would generate a repeat character
0:13:20 > 0:13:21and this was in order to try
0:13:21 > 0:13:24and introduce this apparent randomness into the key.
0:13:26 > 0:13:29The 12 wheels made the machine an awesome generator of code
0:13:29 > 0:13:32and the number of potential ciphering possibilities
0:13:32 > 0:13:33multiplied out as...
0:13:47 > 0:13:52which equalled 1.6 million billion combinations.
0:13:55 > 0:13:57Another innovation saw the Lorenz
0:13:57 > 0:14:02incorporate the natural code of the teleprinter into its basic design.
0:14:03 > 0:14:06It's kind of modern binary code really.
0:14:06 > 0:14:10It's zeroes and ones and they just took the teleprinter code
0:14:10 > 0:14:11and they encrypted that.
0:14:14 > 0:14:18With the Lorenz enciphering device, the plain text letter "A"
0:14:18 > 0:14:23was changed by a machine which actually added to it
0:14:23 > 0:14:26a pseudo-random character, for example, the letter "K"
0:14:26 > 0:14:31might have been used, for which the teleprinter code was this -
0:14:31 > 0:14:36four crosses and a dot and these two characters were then combined
0:14:36 > 0:14:40together by a process which is sometimes called "addition".
0:14:40 > 0:14:45If the two elements were the same then the result was always a dot.
0:14:47 > 0:14:51But if they were different, the answer was a cross.
0:14:51 > 0:14:53And here, they're the same so it's a dot.
0:14:53 > 0:14:56And if you looked at that set of impulses in terms of
0:14:56 > 0:14:58the standard international teleprinter code,
0:14:58 > 0:15:01you would find that that was, in fact, the letter "N".
0:15:01 > 0:15:04The letter "A" has been enciphered to "N"
0:15:04 > 0:15:08by adding this random character "K" to it.
0:15:08 > 0:15:11Now, at the receiving station, of course,
0:15:11 > 0:15:13the letter "N" is the cipher message
0:15:13 > 0:15:18and we already know that that's going to come in, in terms of this pattern.
0:15:18 > 0:15:20And now, a little bit of magic...
0:15:20 > 0:15:24If at the receiving station the same random character that was used
0:15:24 > 0:15:28by the sender was combined with it, in the same way...
0:15:31 > 0:15:36Adding up... Two, these are different so the result's a cross.
0:15:36 > 0:15:39They're different, the result's a cross. Same, a dot.
0:15:39 > 0:15:42These two are the same, a dot. And these two are the same, a dot.
0:15:42 > 0:15:46The result would be that. And if we look back,
0:15:46 > 0:15:48that of course is the old character "A"
0:15:48 > 0:15:51which was the original plaintext.
0:15:52 > 0:15:55The actual number of teleprinters using this code
0:15:55 > 0:15:58in the new network was less than 30.
0:15:58 > 0:16:01But they were the lifeblood of the German command,
0:16:01 > 0:16:03feeding out to the furthest fingertips
0:16:03 > 0:16:05of the Third Reich's reach.
0:16:06 > 0:16:08More importantly,
0:16:08 > 0:16:11as many of the generals needed information about other campaigns
0:16:11 > 0:16:15as well as their own, one line of traffic could produce an insight
0:16:15 > 0:16:18into the entire German war effort.
0:16:18 > 0:16:21This was the prize awaiting the codebreakers.
0:16:24 > 0:16:27To get to it, they had to crack a code no-one understood,
0:16:27 > 0:16:31produced by a machine no-one had seen,
0:16:31 > 0:16:34and with a range of possible encryptions
0:16:34 > 0:16:37that were utterly unimaginable.
0:16:54 > 0:16:57To defeat the impossible machine, Bletchley would turn to
0:16:57 > 0:17:01a 24-year-old mathematician called Bill Tutte.
0:17:10 > 0:17:15Bill was born in Newmarket in 1917, the son of a gardener
0:17:15 > 0:17:18at Fitzroy House, a local racing stable.
0:17:26 > 0:17:30As a child, his keen intelligence soon showed itself.
0:17:30 > 0:17:34He gained a scholarship to Cambridge and County High School.
0:17:36 > 0:17:39After winning the scholarship, Uncle Bill faced
0:17:39 > 0:17:41the even greater feat of getting to and from the school,
0:17:41 > 0:17:44which was roughly a 12-mile journey there
0:17:44 > 0:17:47and then 12 miles back again.
0:17:47 > 0:17:50So he definitely had a lot of determination.
0:17:50 > 0:17:52At his new school he excelled,
0:17:52 > 0:17:54winning prizes in every subject.
0:17:55 > 0:17:59I imagine he might have been frustrated at the school itself
0:17:59 > 0:18:04in that he was apparently so much ahead of all the other pupils
0:18:04 > 0:18:07so he would've been a bit isolated in that respect, I imagine.
0:18:15 > 0:18:18In 1935, he went to Trinity College, Cambridge
0:18:18 > 0:18:21where he studied chemistry and then mathematics.
0:18:22 > 0:18:25Bletchley's habit of raiding the best academic talent
0:18:25 > 0:18:28meant that Bill was sent to the Park in 1941,
0:18:28 > 0:18:31although not everyone recognised his potential.
0:18:31 > 0:18:34He first was interviewed by Alan Turing
0:18:34 > 0:18:38and was not chosen to work on the Enigma project.
0:18:38 > 0:18:43However, that was the best thing that could have happened to Bill.
0:18:43 > 0:18:46Instead, he was chosen by John Tiltman
0:18:46 > 0:18:48to be part of the research group.
0:18:48 > 0:18:52They were the cream of the cryptographic people.
0:18:54 > 0:18:57Bill found himself in the right place at the right time.
0:18:57 > 0:18:59After months of fruitless examination,
0:18:59 > 0:19:02the team working on the invincible Tunny code
0:19:02 > 0:19:04were about to be gifted a way in.
0:19:21 > 0:19:24At the beginning, the Germans were very sloppy.
0:19:24 > 0:19:28They obviously had so much confidence in the machine,
0:19:28 > 0:19:31they were over-confident.
0:19:31 > 0:19:35In fact, this is how we came to break the system.
0:19:36 > 0:19:39You need depth to break any cipher.
0:19:39 > 0:19:43By depth, I mean a number of messages sent using the same key
0:19:43 > 0:19:45or the same system.
0:19:47 > 0:19:5030th August, 1941.
0:19:50 > 0:19:53A German operator had a long message of 4,000 characters
0:19:53 > 0:19:55to be sent from Athens to Vienna.
0:20:02 > 0:20:04What happened is they sent the message
0:20:04 > 0:20:07and the person at the end said, "Well, I didn't quite get that.
0:20:07 > 0:20:09"Can you send it again?"
0:20:23 > 0:20:26The German operator went and sent it again,
0:20:26 > 0:20:29but he didn't change the wheel settings,
0:20:29 > 0:20:33and so we got what we called the depth,
0:20:33 > 0:20:36two messages with exactly the same encryption.
0:20:41 > 0:20:43So he sends the same message
0:20:43 > 0:20:44on the same setting,
0:20:44 > 0:20:48and the trouble is then that when he resends it,
0:20:48 > 0:20:52he makes slight differences in the punctuation,
0:20:52 > 0:20:56so the message isn't quite the same as it was.
0:20:58 > 0:21:02He abbreviated Nummer, the German word for "number", to "Nr",
0:21:02 > 0:21:06so he didn't have to type in the U-M-M-E every time,
0:21:06 > 0:21:09and anything he could abbreviate, he'd abbreviate it.
0:21:12 > 0:21:15An intercept station picked up these messages.
0:21:20 > 0:21:24They realised that they were radio teleprinter.
0:21:28 > 0:21:32The message was sent to Bletchley via a despatch rider.
0:21:32 > 0:21:33When it got there,
0:21:33 > 0:21:38the first person to attack it was legendary codebreaker John Tiltman.
0:21:38 > 0:21:41A former frontline soldier in World War One,
0:21:41 > 0:21:44Tiltman was awarded the Military Cross.
0:21:44 > 0:21:45But it was his talent for languages
0:21:45 > 0:21:50that saw him rise through the ranks in intelligence work.
0:21:50 > 0:21:52He's generally recognised
0:21:52 > 0:21:55as one of Britain's best codebreakers in the Second World war.
0:21:55 > 0:21:59He did achieve quite a lot on Japanese codes, for example.
0:21:59 > 0:22:02He taught himself Japanese in just a few weeks.
0:22:02 > 0:22:06But he looked at this Lorenz cipher and he was the first to realise
0:22:06 > 0:22:09that there was a method of breaking through this code.
0:22:16 > 0:22:19The Lorenz machine had a particular weakness.
0:22:19 > 0:22:22If two messages were sent with the same key sequence,
0:22:22 > 0:22:26then there was a way in which the signals could be recovered.
0:22:26 > 0:22:27Let me show you.
0:22:27 > 0:22:32We had a message earlier where the plaintext was letter A
0:22:32 > 0:22:36and the pseudo-random character generated by the machine was K,
0:22:36 > 0:22:39and the result turned out to be the letter N.
0:22:39 > 0:22:43Now, suppose another plaintext message B was sent
0:22:43 > 0:22:45using the same key.
0:22:46 > 0:22:50Then on this occasion the answer to that in fact turns out to be P.
0:22:50 > 0:22:52I'm not going to show that,
0:22:52 > 0:22:54but it's the same procedure as we used before.
0:22:54 > 0:22:56Now, we saw previously
0:22:56 > 0:23:00that if you add K to this message you recover the plaintext.
0:23:02 > 0:23:04Suppose you add those up,
0:23:04 > 0:23:09so that on the left-hand side you've got A + B + K + K.
0:23:09 > 0:23:12Now, the elements of those two in each case will be identical,
0:23:12 > 0:23:14they'll cancel each other out,
0:23:14 > 0:23:18and in effect the K disappears from the equation.
0:23:18 > 0:23:21And of course, on the right-hand side we've got N + P.
0:23:21 > 0:23:26N + P, from the teleprinter code, is in fact the letter G.
0:23:26 > 0:23:29And so we can say that this is what we've got.
0:23:29 > 0:23:33We've got G, the sum of the two pieces of cipher text,
0:23:33 > 0:23:37and the question is, is it possible to decompose that
0:23:37 > 0:23:42back into the original messages, which were of course A and B?
0:23:42 > 0:23:44That was what we would like to do.
0:23:44 > 0:23:47Well, there's no mathematical way of doing it,
0:23:47 > 0:23:50but one way in which it CAN be done
0:23:50 > 0:23:54is to make an inspired guess for one of those answers.
0:23:54 > 0:23:56Suppose, for example, we made a lucky guess
0:23:56 > 0:24:00that the first message was just the letter A.
0:24:00 > 0:24:04Then if you take the G we've got and add A to it,
0:24:04 > 0:24:08then from the teleprinter code, if you add G and A together
0:24:08 > 0:24:11you discover that you do get B, the second one.
0:24:11 > 0:24:15And so if this make sense, that makes sense, and you've got a result.
0:24:15 > 0:24:19A second, more convincing example, perhaps, is this one,
0:24:19 > 0:24:22which is based upon six letters.
0:24:26 > 0:24:29..is the sum of, in teleprinter world,
0:24:29 > 0:24:33the names of two principal cities in the United Kingdom.
0:24:33 > 0:24:36Now, the question is, could we resolve that
0:24:36 > 0:24:38into the actual names of these cities?
0:24:38 > 0:24:41And the method they used at Bletchley was based upon
0:24:41 > 0:24:44intuition and perseverance.
0:24:44 > 0:24:48For example, if you've got two important towns here,
0:24:48 > 0:24:51it's conceivable that one of them might well be London.
0:24:51 > 0:24:53And so a good try...
0:24:56 > 0:25:00And then proceed to add these pairs of letters together
0:25:00 > 0:25:05using the teleprinter code method I showed you earlier.
0:25:05 > 0:25:07We won't do those. It'll take us too long.
0:25:07 > 0:25:10But I assure you that if you do, you come up with this result.
0:25:13 > 0:25:17Now, it might be argued that that could have occurred by chance,
0:25:17 > 0:25:19but it's very unlikely,
0:25:19 > 0:25:23and so this approach was one that was used at Bletchley Park
0:25:23 > 0:25:26to decompose these combined messages.
0:25:26 > 0:25:29Colonel John Tiltman would take such a message
0:25:29 > 0:25:32and he would use a plausible piece of German,
0:25:32 > 0:25:36something he thought might well occur at the beginning of one of the messages,
0:25:36 > 0:25:38add it into the composite
0:25:38 > 0:25:42and see if something in plausible Germanic came out as a result.
0:25:45 > 0:25:50Tiltman took ten days to hand-break and unravel the transmission.
0:25:52 > 0:25:56In his extraordinary feat, he manages to extract from this
0:25:56 > 0:25:58the cipher text,
0:25:58 > 0:26:01what was the cipher text, what was added to the plaintext.
0:26:01 > 0:26:04It was a phenomenal piece of decryption.
0:26:04 > 0:26:07But it still didn't help the team understand
0:26:07 > 0:26:09how they could regularly read Tunny.
0:26:09 > 0:26:12He couldn't work out the system -
0:26:12 > 0:26:15how the machine worked,
0:26:15 > 0:26:18and the job was passed to Bill Tutte.
0:26:18 > 0:26:23Tutte sort of recalls it as almost an act of desperation -
0:26:23 > 0:26:27"Oh, well, we can't work it out - here you are, you have a go at it,"
0:26:27 > 0:26:30almost disparagingly, you know?
0:26:30 > 0:26:32And Tutte sits down and he sees patterns.
0:26:32 > 0:26:34He's looking for patterns.
0:26:45 > 0:26:51And he did put this 4,000-word message into columns
0:26:51 > 0:26:54and made a rectangle out of it,
0:26:54 > 0:26:58and he thought about what might be a useful length of this.
0:26:58 > 0:27:01And then he noticed that there were certain repetitions
0:27:01 > 0:27:03that went across the rectangle.
0:27:08 > 0:27:16He realises that there seems to be a pattern every 23 times, a rotation.
0:27:16 > 0:27:21He thinks it might be 25, so he tries multiplying 23 by 25
0:27:21 > 0:27:25to see if the pattern extends along that.
0:27:25 > 0:27:27And it doesn't quite work,
0:27:27 > 0:27:33but the pattern does extend along 574.
0:27:33 > 0:27:36So he thinks then,
0:27:36 > 0:27:39"Ah, well, maybe it's 41,"
0:27:39 > 0:27:43because 41 is a prime number of 574.
0:27:43 > 0:27:49You wouldn't have a machine that rotated through 574 positions.
0:27:49 > 0:27:52"Maybe it's 41." And he tried it, and it worked.
0:28:03 > 0:28:06From that, he began to deduce,
0:28:06 > 0:28:10"Well, this starts repeating itself after 41 strokes,"
0:28:10 > 0:28:12that you get a certain resonance
0:28:12 > 0:28:15that even though it's affected by other impulses,
0:28:15 > 0:28:21the dominant thing is here the fact that you get this resonance after 41.
0:28:21 > 0:28:25So he says, "Well, I think the first wheel in this has 41 spokes."
0:28:25 > 0:28:28Then he starts working on the second wheel, and so forth.
0:28:28 > 0:28:34I was working in the same office as Bill Tutte for most of that time,
0:28:34 > 0:28:40and I can still remember him staring into the middle distance
0:28:40 > 0:28:45and making counts on reams and reams of paper.
0:28:47 > 0:28:51And I used to wonder whether he was actually doing anything!
0:28:51 > 0:28:55My word, he was! The most extraordinary achievement.
0:28:58 > 0:29:02Using Tutte's insight and a method known as Turingery,
0:29:02 > 0:29:05the Testery applied brute mental force to break the code.
0:29:05 > 0:29:07As they did, it became apparent
0:29:07 > 0:29:10just what a valuable source of information Tunny would prove to be.
0:29:10 > 0:29:16We saw the signatories and we saw who the messages were sent to.
0:29:16 > 0:29:19So we were well aware of all that.
0:29:19 > 0:29:21And they included
0:29:21 > 0:29:25Field Marshal Keitel, who was the head of the whole German army,
0:29:25 > 0:29:27which was not a bad start,
0:29:27 > 0:29:31and Jodl, who was the Chief of Staff of the German army,
0:29:31 > 0:29:34in other words the chief operating officer,
0:29:34 > 0:29:36and his number two, Warlimont.
0:29:36 > 0:29:39But in 1944 they were joined by a fourth -
0:29:39 > 0:29:43Adolf Hitler himself.
0:29:45 > 0:29:49You're almost in the High Command meeting,
0:29:49 > 0:29:53where they're working it all out. You are almost actually the fly on the wall.
0:29:53 > 0:29:57The world's toughest code had been broken.
0:29:57 > 0:29:59Hitler's secrets were laid bare,
0:29:59 > 0:30:02and the course of the war was about to change,
0:30:02 > 0:30:04all because of one sloppy, lazy error
0:30:04 > 0:30:07by a lowly teleprinter operator.
0:30:07 > 0:30:14I think this German operator did us such a huge favour,
0:30:14 > 0:30:17I think there ought to be a statue of him in Whitehall.
0:30:38 > 0:30:42The first chance for Bletchley Park to use Tunny information in the field
0:30:42 > 0:30:45came at the battle of Kursk on the eastern front.
0:30:45 > 0:30:48The Testery, the elite group commanded by Major Ralph Tester,
0:30:48 > 0:30:52were still breaking this impenetrable code by hand.
0:30:52 > 0:30:56Even so, they had uncovered an incredible amount of information
0:30:56 > 0:30:59regarding plans for a massive surge by Germany
0:30:59 > 0:31:01against the Russian forces.
0:31:01 > 0:31:04The Tunny decrypt showed that they were about to make
0:31:04 > 0:31:08a major assault on the Russian lines,
0:31:08 > 0:31:10and we were able to warn the Russians.
0:31:18 > 0:31:20But much more than that,
0:31:20 > 0:31:24we were able to tell them how the attack was planned.
0:31:24 > 0:31:27"It's going to be a pincer attack."
0:31:27 > 0:31:29And even more astonishingly,
0:31:29 > 0:31:33we were able to give them the whole order of battle.
0:31:35 > 0:31:38It was the Nazis' last chance to put the Red Army on the back foot,
0:31:38 > 0:31:42but the Russians, forewarned and forearmed, were waiting for them.
0:31:42 > 0:31:45Kursk was both the largest armoured clash in history
0:31:45 > 0:31:49and the single bloodiest day of aerial warfare ever.
0:31:51 > 0:31:55By the end of it, Germany's Russian campaign was in tatters
0:31:55 > 0:31:59and the Red Army gained an initiative they would press all the way to Berlin.
0:31:59 > 0:32:06The Russians, of course, called Kursk "the turning of the tide".
0:32:16 > 0:32:20Kursk proved just how important intercepted Tunny messages could be.
0:32:20 > 0:32:24The challenge now was to accelerate the decoding process.
0:32:27 > 0:32:31I've got a page up here that mentions Bill Tutte.
0:32:32 > 0:32:35It says that he invented what they call...
0:32:35 > 0:32:41the "1 + 2 break-in method was invented by William Tutte in November 1942."
0:32:41 > 0:32:43What Bill did, his first achievement was
0:32:43 > 0:32:46he actually diagnosed the machine, the structure of the machine
0:32:46 > 0:32:50and how the cipher worked, purely from intercepted messages.
0:32:50 > 0:32:53Nobody had actually seen the machine at all.
0:32:54 > 0:32:57But then, his second major contribution
0:32:57 > 0:33:01was working out a statistical method of cracking the machine.
0:33:01 > 0:33:05The hand methods that they had used up until then were no longer possible
0:33:05 > 0:33:08because of extra German security measures and so on,
0:33:08 > 0:33:12so they were coming to an end of what they could do in cracking these messages.
0:33:12 > 0:33:15And then Tutte worked out this method.
0:33:15 > 0:33:20It was a mathematical and statistical attack on the coded messages,
0:33:20 > 0:33:23and it required a huge amount of checking and counting of data.
0:33:23 > 0:33:26Luckily, at Bletchley Park there was a man who had an idea
0:33:26 > 0:33:29how this work could be done.
0:33:38 > 0:33:41Putting Bill Tutte's theories into practice
0:33:41 > 0:33:44led to one of the great technological breakthroughs
0:33:44 > 0:33:45of the Second World War,
0:33:45 > 0:33:48a breakthrough kept secret for nearly 60 years.
0:33:54 > 0:33:59It was made by a GPO engineer called Tommy Flowers.
0:34:01 > 0:34:03Flowers was a brilliant man.
0:34:03 > 0:34:06He was quiet, he had a slightly hesitant manner.
0:34:06 > 0:34:08He looked very boyish,
0:34:08 > 0:34:13and with his hair perpetually smarmed back with Brilliantine,
0:34:13 > 0:34:16he didn't look like someone who was about to change the world.
0:34:16 > 0:34:18But change the world he did.
0:34:19 > 0:34:23Tommy Flowers was born in Poplar, London in 1905,
0:34:23 > 0:34:25the son of a bricklayer.
0:34:25 > 0:34:26He was born into
0:34:26 > 0:34:28a Cockney-speaking world,
0:34:28 > 0:34:32and Flowers kept his accent, to a greater or lesser degree,
0:34:32 > 0:34:33right through his life,
0:34:33 > 0:34:35and he said later in life
0:34:35 > 0:34:40that his Cockney accent had probably been a handicap to him.
0:34:40 > 0:34:43His brilliant mind enabled him
0:34:43 > 0:34:46to move out of that world into a quite different world.
0:34:48 > 0:34:51Like Tutte, he was a scholarship boy,
0:34:51 > 0:34:54but he would gravitate to industry rather than university.
0:34:54 > 0:34:57First, he did an apprenticeship in mechanical engineering
0:34:57 > 0:34:59before gaining a degree at night school
0:34:59 > 0:35:02and rounding off his education at Dollis Hill,
0:35:02 > 0:35:06the Post Office's unique research laboratory in London.
0:35:08 > 0:35:11Bletchley used the Dollis Hill engineers to help with their attempts
0:35:11 > 0:35:14to harness machines to the task of codebreaking.
0:35:14 > 0:35:19This is how Tommy came on to the radar of a pivotal figure at the park,
0:35:19 > 0:35:22the mathematician Max Newman.
0:35:22 > 0:35:24He discovered that you could mechanise
0:35:24 > 0:35:27Tutte's method of breaking this cipher.
0:35:27 > 0:35:30He understood that it was something that you could put into a machine.
0:35:30 > 0:35:34Max's department, called the Newmanry,
0:35:34 > 0:35:37had built a machine to crack Tunny.
0:35:37 > 0:35:41Nicknamed Heath Robinson, it kept breaking down.
0:35:43 > 0:35:46Newman brought in Flowers to fix the Robinson,
0:35:46 > 0:35:48but Tommy had a better idea.
0:35:49 > 0:35:52Tommy Flowers took one look at this and said, "I can do that better."
0:35:52 > 0:35:56I can have the patterns generated in electronic circuits,
0:35:56 > 0:36:02and now I've only got one tape, which is the source tape, the cipher text.
0:36:02 > 0:36:06I can read that now at 5,000 characters per second,
0:36:06 > 0:36:09compared with 1,000 on Heath Robinson.
0:36:09 > 0:36:13And I can now generate these patterns in electronic circuits.
0:36:13 > 0:36:17But, of course, that meant that he had to have
0:36:17 > 0:36:20vast numbers of valve tubes in order to do this.
0:36:20 > 0:36:23Valves were flaky kind of devices,
0:36:23 > 0:36:27and the more of them that you had, the greater the probability
0:36:27 > 0:36:30that a couple of them would be out of action at any time.
0:36:30 > 0:36:34But Tommy's practical experience meant that at that time,
0:36:34 > 0:36:37he knew more about the potential of this technology
0:36:37 > 0:36:39than anyone else in the country.
0:36:39 > 0:36:43He knew that if you left electronic valves running for a long time
0:36:43 > 0:36:45then you didn't get problems with them.
0:36:45 > 0:36:49The problems arose if you kept switching them on and off.
0:36:49 > 0:36:50Flowers knew he was right,
0:36:50 > 0:36:54so he just went back to his laboratory at Dollis Hill
0:36:54 > 0:36:57and quietly got on with building the electronic machine
0:36:57 > 0:37:00that he knew the codebreakers needed.
0:37:17 > 0:37:21It was massive, the effort that was required to do it.
0:37:21 > 0:37:26Flowers told me that he and his group worked until their eyes dropped out.
0:37:26 > 0:37:30Eventually, he produces this thing and they try it out,
0:37:30 > 0:37:32and it works first time.
0:37:32 > 0:37:35"Oh, gosh, that's luck." So they try it out again.
0:37:35 > 0:37:39And it works second time, and it keeps working,
0:37:39 > 0:37:43every time they try it out. And they're so...you know,
0:37:43 > 0:37:49"Good grief!" And he produces this thing called Colossus,
0:37:49 > 0:37:56which is the world's first semi-programmable electronic computer.
0:38:16 > 0:38:19This is Colossus.
0:38:19 > 0:38:22And what it did was, you took the intercepted cipher text,
0:38:22 > 0:38:26on a lot of paper tape.
0:38:26 > 0:38:31Five bit code there. And that is received by us on our radio station,
0:38:31 > 0:38:32planked on a paper tape,
0:38:32 > 0:38:36and loaded on to this part of Colossus here, called the bedstick.
0:38:36 > 0:38:39That's the part of Colossus that holds the intercepted
0:38:39 > 0:38:42cipher signal, and that is joined into a loop,
0:38:42 > 0:38:44and being read continuously.
0:38:44 > 0:38:47And that is being read at 5,000 characters per second.
0:38:47 > 0:38:49That's the data going into Colossus.
0:38:49 > 0:38:55They put the results of those readings up on to a lamp panel here,
0:38:55 > 0:39:00and here are the results of a particular run.
0:39:00 > 0:39:05So this is refreshed every time the tape goes round one continuous cycle.
0:39:05 > 0:39:08We got one document that was written at the end of the war.
0:39:08 > 0:39:11A Technical Description of Colossus 1.
0:39:11 > 0:39:13It's a sort of technical manual that describes
0:39:13 > 0:39:17the different types of valves that were used, for example.
0:39:17 > 0:39:20And the different parts of the machine,
0:39:20 > 0:39:22the circuit diagrams of the valves
0:39:22 > 0:39:26that were used in the different parts of the machinery.
0:39:26 > 0:39:30Internal bitstream generators, the clock pulse system and what have you.
0:39:30 > 0:39:35Which were all, nowadays are standard parts of any computer,
0:39:35 > 0:39:39but all had to be invented for this machine from scratch.
0:39:39 > 0:39:43Now, as I say, they have been taken over and used in modern day computers.
0:39:44 > 0:39:49As innovative as it was, Colossus would only break the two chi wheels.
0:39:49 > 0:39:52Decoding Tunny would still be a team effort.
0:39:52 > 0:39:56There were seven stages to the breaking of Tunny.
0:39:56 > 0:39:59And, uh, whilst the Newmanry was established,
0:39:59 > 0:40:02the Newmanry handled two of them,
0:40:02 > 0:40:07and then the Testery handled the other five.
0:40:07 > 0:40:11PHONE RINGS
0:40:21 > 0:40:25Bletchley Park's scepticism was immediately cured
0:40:25 > 0:40:27as soon as they sa2 Colossus working.
0:40:27 > 0:40:29They wanted more machines.
0:40:31 > 0:40:35A little unrealistically, they asked for four more Colossi
0:40:35 > 0:40:38by the 1st June, the projected date for D-Day.
0:40:38 > 0:40:41As it was, Tommy and his team
0:40:41 > 0:40:46only just managed to deliver one more machine, the Mark II.
0:40:49 > 0:40:50It was 1am on the 1st June,
0:40:50 > 0:40:56and Flowers and his men just had to go home to catch some sleep.
0:40:56 > 0:41:00Flowers left one of his right-hand men, Bill Chandler,
0:41:00 > 0:41:04to carry on the fight alone, through the small hours of the morning.
0:41:04 > 0:41:09It was a very tough night for Chandler. He worked on, and about 3am
0:41:09 > 0:41:14he noticed that his feet were in a pool of water.
0:41:14 > 0:41:17A radiator pipe on the wall had burst
0:41:17 > 0:41:22and water was inching inexorably across the floor
0:41:22 > 0:41:24towards high-voltage equipment.
0:41:24 > 0:41:27It was quite dangerous, I think, for Chandler, but he carried on
0:41:27 > 0:41:30and eventually, in the wee small hours,
0:41:30 > 0:41:32he tracked down the fault
0:41:32 > 0:41:36and he made some adjustments using his soldering iron,
0:41:36 > 0:41:39and Flowers turned up a few hours later to find
0:41:39 > 0:41:40Colossus working perfectly.
0:41:40 > 0:41:44No one had managed to fix the leaking radiator pipe, though,
0:41:44 > 0:41:47and the people operating Colossus had to wear Wellington boots
0:41:47 > 0:41:49to insulate themselves.
0:41:49 > 0:41:51But, Flowers beat the deadline.
0:41:51 > 0:41:53It was the 1st June and Colossus was working.
0:41:55 > 0:41:59And so both Colossus I and Colossus II were in operation
0:41:59 > 0:42:01in time for the D-Day landings.
0:42:03 > 0:42:07Tunny decrypts made two major contributions to the success of D-Day.
0:42:07 > 0:42:11The first was to uncover the entire defensive structure
0:42:11 > 0:42:12of the German army.
0:42:12 > 0:42:14The most important information
0:42:14 > 0:42:17that Lorenz provided for the run-up to D-Day
0:42:17 > 0:42:19was the order of battle information,
0:42:19 > 0:42:24which give details of the aircraft, the tanks and so on
0:42:24 > 0:42:29that were available to the Germans against the D-Day forces.
0:42:29 > 0:42:32None of this information came from Enigma intercept.
0:42:32 > 0:42:35Even got details of aircraft being refitted
0:42:35 > 0:42:38or moved around and so on.
0:42:38 > 0:42:41So we had as much information about the German air force
0:42:41 > 0:42:42as the German air force itself had.
0:42:46 > 0:42:48The other contribution was to eavesdrop
0:42:48 > 0:42:50on conversations which confirmed
0:42:50 > 0:42:53that the Nazis had fallen for Operation Fortitude,
0:42:53 > 0:42:55the fake invasion of Calais.
0:42:58 > 0:43:01Hitler had swallowed our deception campaigns,
0:43:01 > 0:43:05Hitler was convinced the attack was coming across the Straits of Dover,
0:43:05 > 0:43:07and that Normandy was a feint.
0:43:11 > 0:43:14These generals, being professionals,
0:43:14 > 0:43:17wanted it to be in the Normandy region.
0:43:20 > 0:43:26Hitler won out, so we knew that the Normandy region
0:43:26 > 0:43:31was less well-defended than it could have been.
0:43:55 > 0:43:58As the war through Europe progressed,
0:43:58 > 0:44:00the information gained from the Tunny system
0:44:00 > 0:44:03began to be used in a more subtle and innovative way.
0:44:07 > 0:44:10The effect of this flow of information
0:44:10 > 0:44:11helped us to "read" Hitler,
0:44:11 > 0:44:14and predict the way he would react and wage war.
0:44:16 > 0:44:19In modern terms, it helped us to get inside his head,
0:44:19 > 0:44:23something which up until then had been difficult to do,
0:44:23 > 0:44:26because Hitler didn't act like a normal military commander.
0:44:28 > 0:44:32They had to learn not to think that Hitler would do what they would do,
0:44:32 > 0:44:36but to understand how Hitler would actually react in these situations,
0:44:36 > 0:44:39and do things that they simply didn't expect him to do.
0:44:39 > 0:44:41To hang on to territory when it was completely pointless.
0:44:41 > 0:44:48And this was one of the amazing things about the war in Italy,
0:44:48 > 0:44:51which people don't really get or understand.
0:44:51 > 0:44:56Once the British know from this teleprinter link
0:44:56 > 0:44:59that the Germans have decided to keep the front going,
0:44:59 > 0:45:03not only do they know how to shape the immediate battle,
0:45:03 > 0:45:06but they also realise that they can keep the thing going
0:45:06 > 0:45:09for as long as they like.
0:45:09 > 0:45:15They can control the extent to which the battle moves forward.
0:45:15 > 0:45:19And by doing so, can drain away German resources,
0:45:19 > 0:45:24which won't then be used for the main battle, the invasion of Europe.
0:45:29 > 0:45:31This is the great irony of the Nazis' love affair
0:45:31 > 0:45:34with secrets and machines.
0:45:34 > 0:45:38The very devices they trusted to give them total security
0:45:38 > 0:45:42allowed the Allies to play Hitler like a fish on a line.
0:45:42 > 0:45:46From the beginning, the Nazis were in the impossible position
0:45:46 > 0:45:48of having to trust these machines.
0:45:48 > 0:45:51Machines which would prove to be an Achilles heel.
0:45:52 > 0:45:56The Nazi philosophy led them to distrust people
0:45:56 > 0:45:59and to put their trust in machines,
0:45:59 > 0:46:02and the problem then is you have to accept the idea
0:46:02 > 0:46:05that the machine cannot be broken.
0:46:05 > 0:46:07And in fact, all of these machines are vulnerable
0:46:07 > 0:46:10provided you approach it in the right way
0:46:10 > 0:46:12and that is what the British did.
0:46:12 > 0:46:14And the secrets of Nazi Germany, of Hitler himself,
0:46:14 > 0:46:17flowed forth because of that.
0:46:17 > 0:46:22Unlike here in Britain, where we had one codebreaking organisation,
0:46:22 > 0:46:24in Germany, there were seven different organisations
0:46:24 > 0:46:26involved in codebreaking.
0:46:26 > 0:46:29And they spent a lot of their time just fighting one another -
0:46:29 > 0:46:33even, on one occasion, actually physically fighting on the street.
0:46:33 > 0:46:35So it couldn't bring together a mass of people
0:46:35 > 0:46:38and get the best out of them in the way in which we did in Britain.
0:46:40 > 0:46:43Similarly, their ideology meant they were equally ill-equipped
0:46:43 > 0:46:45to create their own version of Bletchley Park.
0:46:45 > 0:46:48Some people say it's because the kind of people
0:46:48 > 0:46:51that worked at Bletchley Park
0:46:51 > 0:46:54were just, by German lights, unemployable.
0:46:54 > 0:46:57There were gays like Turing, there were Jews,
0:46:57 > 0:47:01there were totally disorganised academics,
0:47:01 > 0:47:04people who were brilliant but practically dysfunctional.
0:47:04 > 0:47:07They just did not fit into the Nazi ethos.
0:47:17 > 0:47:21By May 1945, the war in Europe was over,
0:47:21 > 0:47:23and Bletchley Park had done its job.
0:47:36 > 0:47:40The war cost, on average, ten million lives a year.
0:47:40 > 0:47:43This is not counting the wounded and the maimed.
0:47:46 > 0:47:50Breaking Tunny at that juncture was pretty jolly important.
0:47:52 > 0:47:55For Tutte, and for Flowers in particular,
0:47:55 > 0:47:59peacetime would bring a unique set of difficulties.
0:48:16 > 0:48:20During the war, Bletchley operated behind a wall of silence.
0:48:20 > 0:48:22And thanks to the nature of their work,
0:48:22 > 0:48:26that secrecy would remain intact for a long time to come.
0:48:26 > 0:48:30Even once the war was over, they still couldn't say.
0:48:30 > 0:48:34That was a big issue, and the bosses at the time understood
0:48:34 > 0:48:36that that was a security threat, if you like,
0:48:36 > 0:48:39so they moved quickly to say to people,
0:48:39 > 0:48:43"Sorry, you've got to keep this secret permanently, forever.
0:48:43 > 0:48:46"You can't go home and tell your mother or your father
0:48:46 > 0:48:48"what you were doing."
0:48:48 > 0:48:51And there are many interesting and quite tragic stories
0:48:51 > 0:48:55where people didn't, and right into the 1970s and beyond,
0:48:55 > 0:48:58parents died without knowing what their children had done.
0:48:59 > 0:49:03As for the machine itself, after the war, Churchill let it be known
0:49:03 > 0:49:06that Colossus had been broken into pieces.
0:49:06 > 0:49:08This was not true.
0:49:08 > 0:49:12At least two survived and were taken to the new GCHQ building,
0:49:12 > 0:49:14where they were used until the 1960s.
0:49:16 > 0:49:20It seems very likely to me that the Russians were using Tunny
0:49:20 > 0:49:22in the Cold War period.
0:49:22 > 0:49:25As the Russian armies swept across Europe,
0:49:25 > 0:49:29they captured numerous German Tunny machines,
0:49:29 > 0:49:32and they very probably reconditioned them
0:49:32 > 0:49:35and used them for their own communications.
0:49:37 > 0:49:41As the Tunny brick was being buried, Tommy was recalled to Dollis Hill.
0:49:42 > 0:49:46While he was there, the Americans announced that they had built
0:49:46 > 0:49:50the world's first computer, ENIAC, in February 1946.
0:49:51 > 0:49:56Already, the true history of computing was being corrupted.
0:49:56 > 0:50:00Tommy's suffering in silence was slowly disappearing from history.
0:50:08 > 0:50:12As for Bill Tutte, he was awarded a fellowship at Cambridge,
0:50:12 > 0:50:15before moving to Canada, where he took up a teaching post
0:50:15 > 0:50:17and met his wife, Dorothea.
0:50:28 > 0:50:31Bizarrely for a man who had helped defeat the Nazis
0:50:31 > 0:50:34with the use of cutting-edge technology,
0:50:34 > 0:50:36Bill settled in rural Montrose,
0:50:36 > 0:50:38surrounded by German-speaking Amish farmers.
0:50:47 > 0:50:49There, he continued to do breakthrough work
0:50:49 > 0:50:51at the University of Waterloo,
0:50:51 > 0:50:55in a branch of mathematics that was growing in importance
0:50:55 > 0:50:57thanks to the rise of computer science.
0:51:01 > 0:51:05So he was working in an area of mathematics
0:51:05 > 0:51:08that wasn't especially fashionable in the middle of the 20th century,
0:51:08 > 0:51:12but it is the mathematics that underlies
0:51:12 > 0:51:14much of the theory of computation.
0:51:14 > 0:51:18So the importance of his work in the field he helped nurture
0:51:18 > 0:51:20became astronomically important,
0:51:20 > 0:51:23as the information age unfolded in the late 20th century.
0:51:23 > 0:51:25Well, all that was rather nice,
0:51:25 > 0:51:32and you see it meant that in the case of unit resistances,
0:51:32 > 0:51:35all these determinants were integers,
0:51:35 > 0:51:40and therefore if you made the horizontal side equal to the complexity,
0:51:40 > 0:51:45all your little squares and rectangle sides,
0:51:45 > 0:51:47they all became integers.
0:51:47 > 0:51:51Certainly, we're talking about a genius, yes, in many respects.
0:51:51 > 0:51:54I think for what he did at Bletchley, he proved it,
0:51:54 > 0:51:56and for what he did in graph theory
0:51:56 > 0:51:59and related parts of mathematics, he proved it again.
0:52:01 > 0:52:06Meanwhile, the story of Colossus was beginning to creep out.
0:52:07 > 0:52:10Tommy at last began to receive some recognition.
0:52:10 > 0:52:13In 1982, he was invited to talk
0:52:13 > 0:52:16at the Museum of Digital Technology in Boston.
0:52:18 > 0:52:22When the hostilities commenced in Europe in 1939,
0:52:22 > 0:52:27all civil work in Britain had to be subordinated to war work.
0:52:27 > 0:52:30In the course of which I was sent to Bletchley Park,
0:52:30 > 0:52:33a highly secret establishment some 50 miles north of London,
0:52:33 > 0:52:36to take on some top-secret work.
0:52:36 > 0:52:40He was still consulting with the MoD as to what he could and couldn't say
0:52:40 > 0:52:43and some things were restricted even in the 1980s.
0:52:43 > 0:52:46For Tommy, 12 years older than Bill,
0:52:46 > 0:52:49the gradual lifting of secrecy came too late.
0:52:49 > 0:52:54Although he did live long enough to see his famous machine rebuilt at Bletchley.
0:52:54 > 0:52:58He knew that history had treated him badly.
0:52:58 > 0:53:01I had the sense that he was weighed down
0:53:01 > 0:53:04by all those might-have-beens,
0:53:04 > 0:53:10how fabulous it could have been if things had gone differently.
0:53:10 > 0:53:12If only it hadn't been for the secrecy.
0:53:12 > 0:53:14He also knew - and told me -
0:53:14 > 0:53:18that the story was coming out too late for him.
0:53:18 > 0:53:22It was too late to make any real difference.
0:53:23 > 0:53:26Back in Canada, Bill took the opportunity provided by
0:53:26 > 0:53:30his 80th birthday lecture to finally break his silence on Tunny.
0:53:30 > 0:53:33And then, if you know the wheel patterns...
0:53:33 > 0:53:35INDISTINCT
0:53:35 > 0:53:39..you can try the first chi wheel
0:53:39 > 0:53:42against the first impulse...
0:53:43 > 0:53:47He said that when he finally did tell about it,
0:53:47 > 0:53:52finally did speak of it, then it lifted an enormous burden,
0:53:52 > 0:53:54and it's hard to exactly say
0:53:54 > 0:53:58to the extent to which it may have altered his personality,
0:53:58 > 0:54:02the personality that I first met him as.
0:54:10 > 0:54:14Outside of a select group of academics, however,
0:54:14 > 0:54:17few people realise the significance of these men's achievements.
0:54:17 > 0:54:21Bill received the Order of Canada for his academic work,
0:54:21 > 0:54:25but he was never decorated by his own country.
0:54:40 > 0:54:44He did, however, gain the most important award he could have wished for.
0:54:48 > 0:54:50To become a Fellow of the Royal Society
0:54:50 > 0:54:54and to sign this charter book, you need to be a leading scientist,
0:54:54 > 0:54:59you need to convince your peers that your work is good enough.
0:55:00 > 0:55:04So you are refereed in the same way that a scientific paper is refereed.
0:55:04 > 0:55:08If you cross that hurdle, Council of the Royal Society
0:55:08 > 0:55:11will assess you as being a good enough scientist,
0:55:11 > 0:55:14you become a Fellow, and if you get over that hurdle,
0:55:14 > 0:55:17then you become a Fellow of the Royal Society
0:55:17 > 0:55:20and you sign this very fine book.
0:55:20 > 0:55:23It helps if you have a Nobel Prize tucked away somewhere.
0:55:23 > 0:55:26In 1987, Bill signed the book.
0:55:26 > 0:55:29He joined an illustrious group.
0:55:29 > 0:55:31Isaac Newton,
0:55:31 > 0:55:34Charles Darwin, Winston Churchill,
0:55:34 > 0:55:37and William T Tutte.
0:55:38 > 0:55:42Other names in the book are Alan Turing and Max Newman.
0:55:42 > 0:55:45Tommy's name was never entered in it,
0:55:45 > 0:55:46although one of his many awards
0:55:46 > 0:55:49does show the effect of the revolution he helped begin.
0:55:49 > 0:55:51When personal computers came in
0:55:51 > 0:55:54in the 1980s and '90s, he bought a PC,
0:55:54 > 0:55:58tried to work out how to use it and had difficulty,
0:55:58 > 0:56:01so he enrolled on a course at the local college
0:56:01 > 0:56:04to learn basic information processing,
0:56:04 > 0:56:08and he got a certificate, here,
0:56:08 > 0:56:11which shows that he passed an introductory course
0:56:11 > 0:56:13in information processing,
0:56:13 > 0:56:18so he learned how to use programs on a PC like everyone else,
0:56:18 > 0:56:23and that was 28th June 1993, when he was 87 years old.
0:56:25 > 0:56:29Tommy's only public recognition was to have a road
0:56:29 > 0:56:32and an IT centre named after him in his native East End.
0:56:35 > 0:56:38The centre has since been closed.
0:56:38 > 0:56:40At the end of the war,
0:56:40 > 0:56:44Flowers got a leading inventors award for his war work,
0:56:44 > 0:56:49and this carried a monetary reward of £1,000,
0:56:49 > 0:56:52which was quite a lot of money in those days, of course,
0:56:52 > 0:56:54but Flowers being Flowers,
0:56:54 > 0:56:59he shared it with his men, and so by the time he had done that,
0:56:59 > 0:57:05he'd got about 350 quid for inventing the first electronic computer.
0:57:10 > 0:57:13Tommy died aged 92 in 1998.
0:57:16 > 0:57:19And Bill four years later, aged 84.
0:57:24 > 0:57:26Bill Tutte's memorial
0:57:26 > 0:57:29is a simple headstone in a rural Canadian cemetery,
0:57:29 > 0:57:32and a lifetime of academic achievement.
0:57:32 > 0:57:35Tommy's is slightly different.
0:57:36 > 0:57:40My father was cremated and the ashes scattered in the crematorium,
0:57:40 > 0:57:44but I think he would have recognised that his main memorial
0:57:44 > 0:57:46is at Bletchley Park in the reconstituted Colossus.
0:57:46 > 0:57:49As an engineer, to have a working machine
0:57:49 > 0:57:52as your memorial is the ideal thing, really.
0:57:57 > 0:57:59Hitler ordered this machine himself.
0:57:59 > 0:58:02It should never, ever have been broken.
0:58:03 > 0:58:06But the minds at Bletchley Park
0:58:06 > 0:58:09managed to find ways of breaking it.
0:58:12 > 0:58:18And this is an amazing triumph of mind over machines.
0:58:58 > 0:59:01Subtitles by Red Bee Media Ltd
0:59:01 > 0:59:04E-mail subtitling@bbc.co.uk