0:00:29 > 0:00:34The tiny island of Coreisa is a pinprick of rock out there.
0:00:34 > 0:00:36It's only five miles from the shore,
0:00:36 > 0:00:39but for most, it might as well be Mars.
0:00:41 > 0:00:43No scheduled boats go there,
0:00:43 > 0:00:46so you have to find a local willing to take you.
0:00:47 > 0:00:49I'm seeking four-legged invaders
0:00:49 > 0:00:57discovered on a small isle near here in 1964 by an inquisitive explorer.
0:00:58 > 0:01:00This is Gordon Corbett,
0:01:00 > 0:01:04a curator of mammals at the Natural History Museum in London.
0:01:04 > 0:01:07He'd heard whispers of a mysterious creature living on an island
0:01:07 > 0:01:11in these waters, a colony that had no place being there.
0:01:13 > 0:01:19Locals thought they might be rats, but Gordon had his own suspicions.
0:01:19 > 0:01:21He travelled out to the island
0:01:21 > 0:01:24to catch one and take a specimen back to London.
0:01:24 > 0:01:28This is the animal he caught, he'd found a freshwater vole.
0:01:28 > 0:01:33How had this shy river creature crossed miles of seawater,
0:01:33 > 0:01:37how had it survived marooned on the island?
0:01:37 > 0:01:40It was astonishing to discover water voles
0:01:40 > 0:01:44on tiny isles off Western Scotland.
0:01:44 > 0:01:51Normally they thrive in freshwater, avoiding the perils of the open seas.
0:01:51 > 0:01:54So how did water voles get to this rocky outcrop, Coreisa?
0:01:58 > 0:02:01Did a pregnant female find herself on a passing boat?
0:02:01 > 0:02:04Or were they washed out on sea currents?
0:02:07 > 0:02:10The island of Coreisa is about the size of three football pitches.
0:02:10 > 0:02:15There's little shelter and no running water.
0:02:17 > 0:02:21But for the next two days... this is home.
0:02:21 > 0:02:23'And I've got company.
0:02:23 > 0:02:28'Scientists from Aberdeen University are studying how over generations
0:02:28 > 0:02:33'the voles have adapted to this alien environment.
0:02:33 > 0:02:36'Helping me get settled is biologist Matt Oliver.'
0:02:36 > 0:02:40Well, interestingly the water voles here have a very different
0:02:40 > 0:02:44behaviour and eco type from water voles in the Scottish mainland.
0:02:44 > 0:02:47We've got very little fresh water on this island at all,
0:02:47 > 0:02:50and instead the water voles have a more mole-like existence,
0:02:50 > 0:02:53they live in burrows underneath the ground eating roots and shoots,
0:02:53 > 0:02:55and they don't have many competitors,
0:02:55 > 0:02:58so they've got more or less a free reign of the place.
0:02:58 > 0:03:02These shy creatures aren't too keen to meet us,
0:03:02 > 0:03:04so team leader Stuart Piertney
0:03:04 > 0:03:07is laying a trap baited with tatties and carrots.
0:03:07 > 0:03:11- Put a bit of extra bedding material in.- OK.
0:03:11 > 0:03:14The door closes behind him, simple as that.
0:03:14 > 0:03:16And it doesn't do the vole any harm to be trapped?
0:03:16 > 0:03:18Absolutely not. These guys think of these
0:03:18 > 0:03:21as little mini hotel rooms, they really like the idea
0:03:21 > 0:03:23they can get a good feed. We know that
0:03:23 > 0:03:27because from one day to the next, we'll be catching the same voles.
0:03:27 > 0:03:31With the traps set, we work on our own survival strategy.
0:03:45 > 0:03:48Good morning and good news.
0:03:48 > 0:03:50The water voles have checked into the traps overnight,
0:03:50 > 0:03:53so now it's rise and shine for them too.
0:03:53 > 0:03:57- So the first job is to get him out of the trap.- Yep.
0:03:58 > 0:04:01- And there he is.- They're much bigger than I thought they'd be.
0:04:01 > 0:04:02Yes. They've got hardy tails,
0:04:02 > 0:04:04so you can keep hold of them with the tail
0:04:04 > 0:04:06and he's as happy as Larry in the hand there.
0:04:06 > 0:04:08In essence these guys are all related,
0:04:08 > 0:04:10it's all brothers and uncles and aunties.
0:04:10 > 0:04:14Theory would predict that with a small isolated population like this
0:04:14 > 0:04:16they should have lost their genetic variation,
0:04:16 > 0:04:18which should make them not very fit,
0:04:18 > 0:04:20they should be prone to the effects of parasites,
0:04:20 > 0:04:22but you can see that's not the case at all,
0:04:22 > 0:04:24these guys are looking really healthy,
0:04:24 > 0:04:27so they seem to be bucking the trend one way or another.
0:04:27 > 0:04:30The team are unravelling the genetic puzzle
0:04:30 > 0:04:36of how a healthy colony may have flourished from just one female.
0:04:39 > 0:04:42The findings could help preserve endangered species
0:04:42 > 0:04:45that have dwindled to a few individuals.
0:04:47 > 0:04:51As for the descendants of the original water vole invader,
0:04:51 > 0:04:53they may have become inmates on this island,
0:04:53 > 0:04:57but I can think of worse places to be marooned.
0:05:00 > 0:05:05In 1915, we looked across the North Sea and trembled.
0:05:05 > 0:05:08The Great War was tearing the continent apart.
0:05:10 > 0:05:13And here on the quiet shores of Norfolk
0:05:13 > 0:05:19a terrifying new style of attack was about to be unleashed - by aerial invaders.
0:05:19 > 0:05:23On the night of the 19th of January 1915,
0:05:23 > 0:05:26townsfolk on the dark streets of Great Yarmouth
0:05:26 > 0:05:31were transfixed by an eerie noise from the fog bank above.
0:05:34 > 0:05:39An eyewitness described the sound as 20 bicycles charging down a hill,
0:05:39 > 0:05:42then a brilliant flash appeared in the sky,
0:05:42 > 0:05:47a searchlight from a flying machine illuminated the streets,
0:05:47 > 0:05:49followed by a string of bomb blasts.
0:05:49 > 0:05:54On that foggy night, many people couldn't believe their eyes.
0:05:54 > 0:05:57But later, the local paper left no doubt.
0:05:59 > 0:06:04A Zeppelin air raid - the first on British shores.
0:06:04 > 0:06:06With that attack on Great Yarmouth,
0:06:06 > 0:06:10the Germans unleashed three years of terror.
0:06:10 > 0:06:11Aerial warfare was invented,
0:06:11 > 0:06:15as the invaders outsmarted Britain's defenders.
0:06:16 > 0:06:19Zeppelins were long-range killing machines
0:06:19 > 0:06:23carrying over 1,000lbs of bombs.
0:06:23 > 0:06:27They had hit Norfolk first, but the Germans had a bigger prize.
0:06:27 > 0:06:31In the summer, they struck London.
0:06:31 > 0:06:3295 died there by the year's end,
0:06:32 > 0:06:37and fear spread across the land.
0:06:37 > 0:06:40Historian Graham Mottram knows why we struggled
0:06:40 > 0:06:42to shoot down the airships.
0:06:43 > 0:06:45We were only - what? -
0:06:45 > 0:06:4811 years after the Wright brothers' first flight?
0:06:48 > 0:06:50So aircraft were still very limited.
0:06:50 > 0:06:54We had I think it was 93 aeroplanes, something like that,
0:06:54 > 0:06:56at the outbreak of the First World War, and of course
0:06:56 > 0:07:00the art of anti-aircraft gunnery was still very, very primitive.
0:07:00 > 0:07:05We were looking at trying to modify artillery pieces to try and...
0:07:05 > 0:07:09and shoot high in the air, in the hope of bringing these things down.
0:07:09 > 0:07:11The Zeppelins' night-time blitz
0:07:11 > 0:07:15would strike along the length and breadth of Britain,
0:07:15 > 0:07:19killing hundreds during the First World War.
0:07:19 > 0:07:24We scrambled to invent air defences from scratch.
0:07:24 > 0:07:28The Royal Flying Corps were fighting on the Western Front,
0:07:28 > 0:07:33so early protection of home shores relied largely on Royal Navy aircraft.
0:07:35 > 0:07:38They flew from coastal airstrips,
0:07:38 > 0:07:41and the Navy also tried a desperate new tactic.
0:07:41 > 0:07:45The aim was to intercept the airship raiders over the water,
0:07:45 > 0:07:49which meant taking off from the sea.
0:07:50 > 0:07:54You've got this 60ft long barge - on it there's a wooden deck,
0:07:54 > 0:07:57and on that wooden deck we put a Sopwith Camel.
0:07:57 > 0:08:01Towing it quickly across the North Sea into the teeth of a strong wind
0:08:01 > 0:08:04meant there was enough flying wind across the deck.
0:08:04 > 0:08:06- You'd get lift-off! - You'd get lift-off.
0:08:06 > 0:08:09Let go of the string that secures the aircraft at the back of the boat
0:08:09 > 0:08:11and it leaps into the air.
0:08:11 > 0:08:14This is, effectively, a very early aircraft carrier.
0:08:14 > 0:08:16That is precisely what it is.
0:08:17 > 0:08:22Even if a fighter plane could find a Zeppelin in the pitch darkness,
0:08:22 > 0:08:26it was still a David and Goliath struggle to destroy an airship.
0:08:26 > 0:08:31Look at its size, compared to a fighter plane of the same period.
0:08:31 > 0:08:34It's dwarfed by the Zeppelin.
0:08:34 > 0:08:36To lift men and bombs,
0:08:36 > 0:08:43a vast quantity of lighter-than-air hydrogen gas was contained inside a massive frame.
0:08:46 > 0:08:48The metal skeleton held enough gas-bags
0:08:48 > 0:08:51to survive many hits from a machine gun.
0:08:53 > 0:08:57But the Zeppelin's greatest fear was fire.
0:08:57 > 0:09:00Their hydrogen gas was highly flammable.
0:09:02 > 0:09:07Could anyone conjure up a fiery magic bullet to save Britain from the Zeppelins?
0:09:09 > 0:09:13Tony Edwards knows the secret of the new incendiary ammunition.
0:09:15 > 0:09:18That was filled with phosphorous, and in the side of the bullet
0:09:18 > 0:09:22there was a very, very small hole filled with solder.
0:09:22 > 0:09:23When the bullet was fired,
0:09:23 > 0:09:27the bullet twisted up the barrel in the rifling, the solder melted,
0:09:27 > 0:09:29and as the bullet left the muzzle of the gun,
0:09:29 > 0:09:31it was spewing phosphorous.
0:09:31 > 0:09:35Phosphorus ignites when in contact with the air, it sets light
0:09:35 > 0:09:40and it leaves a smoke trail so it's burning all the way to its target.
0:09:40 > 0:09:42As well as phosphorous shells,
0:09:42 > 0:09:45by 1916 our armoury also included bullets
0:09:45 > 0:09:49with an explosive nitro-glycerine core.
0:09:49 > 0:09:53Now we had the chemical weapons to kill the Zeppelins.
0:09:54 > 0:09:56But it would take brave men to try.
0:10:00 > 0:10:04I've got a precious album that belonged to Egbert Cadbury,
0:10:04 > 0:10:06a courageous Zeppelin hunter.
0:10:07 > 0:10:09Cadbury was based in Great Yarmouth.
0:10:09 > 0:10:11Originally, he was a Navy pilot,
0:10:11 > 0:10:15but in 1918 he was co-opted into the newly formed RAF.
0:10:18 > 0:10:21On the night of the 5th of August 1918,
0:10:21 > 0:10:25Major Cadbury launched the last attack against the airship invaders,
0:10:25 > 0:10:29when the Germans unleashed the super-Zeppelin...
0:10:29 > 0:10:33..the L70 - the most advanced Zeppelin yet.
0:10:34 > 0:10:38Almost 700 feet long, with seven engines,
0:10:38 > 0:10:43capable of carrying 10,000lbs of bombs.
0:10:43 > 0:10:47I've actually got a priceless recording of Major Cadbury
0:10:47 > 0:10:50recounting his struggle against the fearsome Zeppelin
0:10:50 > 0:10:52on that fateful night.
0:10:54 > 0:10:57'We received warning from naval patrols at sea
0:10:57 > 0:11:00'that hostile aircraft were approaching The Wash at great height.
0:11:03 > 0:11:05'I immediately flew off in pursuit.'
0:11:09 > 0:11:13Unbeknown to Cadbury, he wasn't only taking on the super-Zeppelin.
0:11:13 > 0:11:17At the helm was this man, Commander Peter Strasser,
0:11:17 > 0:11:20architect of the Zeppelin war on Britain,
0:11:20 > 0:11:23desperate to prove the worth of his airships against aircraft.
0:11:24 > 0:11:28Despite being three times the length of a jumbo jet,
0:11:28 > 0:11:32the L70 was not easy to find in pitch blackness.
0:11:32 > 0:11:36'You sat in the cockpit, and had to depend upon your eyesight
0:11:36 > 0:11:39'to spot the airship against a starry sky.
0:11:39 > 0:11:43'It was rather like trying to find a fly in a darkened bedroom.'
0:11:43 > 0:11:46The airship was almost over the coast.
0:11:46 > 0:11:49To intercept it Cadbury knew he would have to push his plane
0:11:49 > 0:11:52to altitudes close to its physical limit,
0:11:52 > 0:11:56where the air was so thin the engine was at risk of stalling.
0:11:56 > 0:12:00In an open cockpit at 17,000ft there would have been a biting wind.
0:12:00 > 0:12:03The engine would have been rattling, spitting oil...
0:12:03 > 0:12:06It would have been impossible to hear a Zeppelin over the racket.
0:12:06 > 0:12:11But miraculously, Cadbury caught a glimpse of his prey.
0:12:13 > 0:12:14'She looked simply immense -
0:12:14 > 0:12:18'as indeed she was, being 300 yards long from stem to stern.'
0:12:18 > 0:12:24Held aloft by 2.2 million cubic feet of flammable hydrogen.
0:12:24 > 0:12:28A tiny incendiary bullet could bring the super-Zeppelin down.
0:12:28 > 0:12:33Gunner Bob Leckie made ready with his machine gun.
0:12:33 > 0:12:36'Suddenly the darkness was ripped open.
0:12:36 > 0:12:40'Bob Leckie gave her a few bursts of fire of tracer bullets.'
0:12:44 > 0:12:46A hit!
0:12:46 > 0:12:48'And as I banked away,
0:12:48 > 0:12:51'she went blazing down to the clouds 2,000 feet beneath us.
0:12:53 > 0:12:57'We lost sight of her as she continued her downward journey
0:12:57 > 0:13:00'into the North Sea, nearly three miles below.'
0:13:03 > 0:13:06Strasser, the German Zeppelin commander, fell to his death.
0:13:06 > 0:13:10His ambitious plans for more audacious airship raids
0:13:10 > 0:13:11died with him.
0:13:13 > 0:13:18It started over the Norfolk coast, and it ended there.
0:13:18 > 0:13:23Sir Egbert Cadbury went on to manage his family's chocolate empire,
0:13:23 > 0:13:25but he kept a souvenir.
0:13:25 > 0:13:29This is a cigarette case made from lightweight aluminium taken from
0:13:29 > 0:13:31the super-Zeppelin.
0:13:31 > 0:13:34It actually has Cadbury's signature inscribed on it.
0:13:35 > 0:13:40A small reminder of a largely forgotten first Blitz on Britain,
0:13:40 > 0:13:45when events on this coast shook the nation to its core.