0:00:13 > 0:00:15This is Coast.
0:00:42 > 0:00:45We're celebrating the workers of our shores.
0:00:48 > 0:00:53The east coast of Britain is dotted with industrious communities.
0:00:56 > 0:00:59They strike out across the sea to earn a crust.
0:01:00 > 0:01:04Men who know the price to be paid for landing fish.
0:01:07 > 0:01:10But this harsh life on rolling seas
0:01:10 > 0:01:14relies on the support of those back on land.
0:01:16 > 0:01:18I'm in search of forgotten workers
0:01:18 > 0:01:22who kept our biggest fishing fleet afloat.
0:01:23 > 0:01:25We've arrived in Grimsby.
0:01:28 > 0:01:32This harbour used to be crammed with trawlers.
0:01:32 > 0:01:35At the high watermark of the North Sea Fleet,
0:01:35 > 0:01:38some 300 fishing vessels worked out of Grimsby.
0:01:40 > 0:01:44Magnificent vessels like this were a floating workplace,
0:01:44 > 0:01:48doing business in the wild North Sea.
0:01:49 > 0:01:53The crew scoured the seas for cod and haddock,
0:01:53 > 0:01:57fish that had to be kept fresh for weeks.
0:01:57 > 0:01:59They needed ice, lots of it.
0:01:59 > 0:02:02A challenge the early trawler men had to crack.
0:02:02 > 0:02:07This grand building houses a freezing machine
0:02:07 > 0:02:10constructed on a massive scale.
0:02:10 > 0:02:13This is an ice factory!
0:02:16 > 0:02:18Built in 1901, the Grimsby Ice Factory
0:02:18 > 0:02:22supplied the port's trawlers for nearly a century.
0:02:22 > 0:02:24My guide is Mike Sonley,
0:02:24 > 0:02:29who was the last man out when the factory closed its doors in 1990.
0:02:31 > 0:02:36This precious film was shot just two weeks before production ceased.
0:02:38 > 0:02:40Today, it looks very different.
0:02:43 > 0:02:47This is Mike's first visit back to his old workplace.
0:02:51 > 0:02:54Heartbreaking. I just can't believe it.
0:02:54 > 0:02:57A lump comes in your throat, definitely.
0:02:57 > 0:03:01A real shame. How did that finish up there?
0:03:01 > 0:03:04It was immaculate. You could just eat your dinner off the floor.
0:03:04 > 0:03:06It was spotless.
0:03:06 > 0:03:10I suppose the ice factory was totally essential for the port, for the trawlers.
0:03:10 > 0:03:14We'd come out here at 4:00am and there'd be 20 wagons out there
0:03:14 > 0:03:17waiting for 20 tonnes of ice each.
0:03:17 > 0:03:19It was a fantastic company to work for.
0:03:24 > 0:03:29When this machinery sprang into action, the ice palace came alive.
0:03:30 > 0:03:35These massive engines were used to compress ammonia gas.
0:03:35 > 0:03:41How did that compressed gas produce up to a thousand tonnes of ice a day?
0:03:43 > 0:03:46Chemist Mark Lorch has the answer.
0:03:48 > 0:03:52The first step is really just to get a gas and compress it.
0:03:52 > 0:03:55Now, you can feel that's cold.
0:03:55 > 0:03:59As it comes out it expands and in the process cools down because all the molecules
0:03:59 > 0:04:03are much further apart now. They're not able to bash into each other quite so much.
0:04:04 > 0:04:08That chilling effect is the principle behind all sorts of refrigeration,
0:04:08 > 0:04:11including your domestic fridge and freezer.
0:04:11 > 0:04:15The next step then is to show you how we can make ice with this simple set-up.
0:04:15 > 0:04:20Pour this briny water into here, and what we need to do is to squirt some of this pressurised liquid,
0:04:20 > 0:04:24which will be very cold when it releases, through this coil here
0:04:24 > 0:04:29and in so doing, this whole coil will cool down,
0:04:29 > 0:04:31the salty water will cool down.
0:04:31 > 0:04:36But salty water will go below zero degrees centigrade before it freezes.
0:04:36 > 0:04:40So, if we then take our tube of fresh water,
0:04:40 > 0:04:43put that in there, this tube will freeze.
0:04:43 > 0:04:46Because the brine has a lower freezing point than fresh water,
0:04:46 > 0:04:50it will cool this fresh water in here pretty quickly and that will turn to ice.
0:04:50 > 0:04:52Yeah, that's the hope, yeah.
0:04:52 > 0:04:54So we just need to wait for that to freeze.
0:04:54 > 0:04:59We're minus two, heading for minus three degrees in there now.
0:05:00 > 0:05:05- There you go.- It's solid.- There you go, ice on the dockside.
0:05:07 > 0:05:12This cooling method, scaled up to an industrial process, powered the ice factory.
0:05:12 > 0:05:18It started with piping in the fresh water to be frozen.
0:05:18 > 0:05:21- That there came down. - All these nozzles...
0:05:21 > 0:05:25Came down all in one go, so they filled every pan with water.
0:05:25 > 0:05:29- So the fresh water came out of these pipes, filled those pans... - That's correct.
0:05:29 > 0:05:32So these metal boxes was where the ice actually formed.
0:05:32 > 0:05:36That's it. Just the same as when you put your ice cubes in a fridge.
0:05:36 > 0:05:39But where was the brine that chilled this fresh water?
0:05:39 > 0:05:43Below the pans. If you took all the pans out, it would be just one gigantic swimming pool.
0:05:43 > 0:05:46So you've got hundreds of these metal pans full of fresh water,
0:05:46 > 0:05:50they get filled up here and they get pushed by gigantic rams
0:05:50 > 0:05:53through the brine from one end of this hall to the other.
0:05:53 > 0:05:57And by the time the pans had got to the far end, the water's turned to ice.
0:05:57 > 0:06:02It took 27 hours for the pans to reach the far side of the building,
0:06:02 > 0:06:04gradually being chilled on their journey
0:06:04 > 0:06:07through the super-cooled brine beneath the floorboards.
0:06:09 > 0:06:14So the pans have travelled the full length of the hall, and they've emerged this end and turned into ice.
0:06:14 > 0:06:18That's correct. Then the crane comes along with the hooks, picks it up,
0:06:18 > 0:06:20drops it in the thaw tank, which is warm water.
0:06:20 > 0:06:24As soon as your ice pops up out here in moulds, it's into the cradle then.
0:06:24 > 0:06:28The cradle's balanced with seven and a half tonnes of ice.
0:06:28 > 0:06:31It tips over, slides down, all on to the floor, like. You know.
0:06:34 > 0:06:38Then you fed the ice on to the conveyor into this crusher in the far end here.
0:06:38 > 0:06:41So for the ice factory this is the very end of the process,
0:06:41 > 0:06:46because what's falling out the bottom of the crusher is crushed ice ready for the trawlers.
0:06:46 > 0:06:51That's it, and it takes it up there and on to that conveyor out there and into the ships.
0:06:53 > 0:06:56But as Grimsby's fishing fleet dwindled,
0:06:56 > 0:06:59fewer workers were waiting at the end of the line for ice.
0:07:00 > 0:07:04The factory doors closed in 1990.
0:07:05 > 0:07:08And what was it like that day that you left here,
0:07:08 > 0:07:11the last man to be in here and lock the door for the last time?
0:07:12 > 0:07:14Well, I can't explain it.
0:07:14 > 0:07:17It was like if you'd lost somebody you know in your family really.
0:07:19 > 0:07:21And it was heartbreaking.
0:07:23 > 0:07:25And now to see it like this.
0:07:37 > 0:07:40There's not much market for ice these days in Grimsby harbour,
0:07:40 > 0:07:42but it's still doing brisk business.
0:07:46 > 0:07:52The busiest boats now are those coming and going to service offshore wind farms in the North Sea.
0:07:54 > 0:07:57Workers adapting to our changing coast.
0:07:59 > 0:08:03New technology driving new opportunities.
0:08:03 > 0:08:06It's an old, old story around our shores.
0:08:07 > 0:08:11The Royal Navy has often been at the vanguard of innovation.
0:08:13 > 0:08:16Fine ships have always needed skilled workers.
0:08:17 > 0:08:21Those backroom boffins have given our sailors the edge in battle
0:08:21 > 0:08:24since the days of wooden warships.
0:08:25 > 0:08:31Back then, the Navy's cannonballs flew truer than those of our enemies.
0:08:38 > 0:08:42Their deadly accuracy was largely due to a secret ingredient
0:08:42 > 0:08:45we used to make our shot perfectly round.
0:08:49 > 0:08:52A rare mineral used to manufacture precision cannonballs
0:08:52 > 0:08:54was mined near Whitehaven.
0:09:01 > 0:09:04Tessa is on the mineworkers' trail.
0:09:05 > 0:09:10I'm going back over 200 years to the time of Nelson's Navy.
0:09:12 > 0:09:15At the Battle of Trafalgar, HMS Victory alone
0:09:15 > 0:09:20fired over 2,500 rounds of heavy iron shot.
0:09:25 > 0:09:29At war with Napoleon, the Navy needed lots of ammunition.
0:09:31 > 0:09:34Maritime historian Gareth Cole knows the numbers.
0:09:34 > 0:09:38I have here a couple of receipts which show just how many cannonballs
0:09:38 > 0:09:40were sent to the ordnance by various companies.
0:09:40 > 0:09:44- We've got one here for 100,000 cannonballs.- 100,000?
0:09:44 > 0:09:48100,000 in one delivery, which cost about £8,500.
0:09:48 > 0:09:51Considerable amounts of cash are being parted.
0:09:51 > 0:09:53It was. Over the course of about a 30-year period,
0:09:53 > 0:09:58over the French Revolution and Napoleonic wars, the ordnance spent about £10 million on the Navy,
0:09:58 > 0:10:01which is about £1 billion in today's money.
0:10:04 > 0:10:07Foundries could make a mint from Government contracts.
0:10:07 > 0:10:10But they had their work cut out.
0:10:10 > 0:10:12The Navy wasn't easy to please.
0:10:13 > 0:10:16There's more to cannonballs than meets the eye.
0:10:16 > 0:10:18To fly true and hit the intended target,
0:10:18 > 0:10:23they have to be as round and as smooth and as perfect as possible.
0:10:29 > 0:10:33To appreciate why the plumbago miners were so important,
0:10:33 > 0:10:35we need to find out what plumbago actually is
0:10:35 > 0:10:38and how it helped cast cannonballs.
0:10:38 > 0:10:40So we're going to make our own. Old-style!
0:10:42 > 0:10:47The trade secrets of cannonball casting were lost as the industry dwindled.
0:10:47 > 0:10:51But foundry man Andrew Laing is trying to turn back time.
0:10:55 > 0:10:58The plumbago was a secret process.
0:10:58 > 0:11:01You coat the mould with the plumbago to make it nice and smooth
0:11:01 > 0:11:04when the casting is removed, and this is what we call casting strip
0:11:04 > 0:11:07and so there's no sand sticking to the actual casting.
0:11:07 > 0:11:10The effect it has in the mould is a bit like buttering a baking tray.
0:11:10 > 0:11:12It slips out at the end.
0:11:12 > 0:11:19Plumbago powder stopped the cast iron cannonballs sticking, even when red-hot.
0:11:19 > 0:11:24Nothing else was such a good lubricant, and only we had the best.
0:11:24 > 0:11:28You're smoothing it in with your finger there.
0:11:28 > 0:11:31- Yeah, we're just sleeking it up. - And that's to help it ease out.
0:11:31 > 0:11:33And again to make the ball as smooth as possible.
0:11:33 > 0:11:38When it's being fired. So will I have a go at doing that? Fill in the gouge.
0:11:38 > 0:11:42Plumbago is common today. We know it as graphite or pencil lead.
0:11:44 > 0:11:48But some 200 years ago, high-grade plumbago was rare.
0:11:48 > 0:11:52Whitehaven was close to the only mine for the precious element.
0:11:53 > 0:11:59Plumbago was hard to get, and working with it was a closely guarded commercial secret.
0:11:59 > 0:12:04We haven't a manual for casting cannonballs and we're nowhere near a foundry.
0:12:04 > 0:12:06Can we manage it on the quayside?
0:12:07 > 0:12:11- Which one have we got?- Any one. - Go on. Go on.
0:12:12 > 0:12:13That's it.
0:12:15 > 0:12:17So, the moment of truth.
0:12:17 > 0:12:20Will our graphite lining, in other words the plumbago,
0:12:20 > 0:12:24have delivered a perfectly formed smooth cannonball? No pressure.
0:12:30 > 0:12:34Oh, it's a disaster! There isn't one.
0:12:34 > 0:12:37It's not run. The metal's chilled.
0:12:37 > 0:12:44The sea breeze cooled my molten iron so quickly, it didn't flow into the mould.
0:12:44 > 0:12:46Of course, you did cast it!
0:12:49 > 0:12:52But these wily lads have left nothing to chance.
0:12:52 > 0:12:55They've brought cannonballs cast in their foundry.
0:12:55 > 0:12:58Half the mould with plumbago, half without.
0:12:59 > 0:13:04You can see the surface finish on that one, the effects of the plumbago.
0:13:04 > 0:13:07Yeah, you can immediately. I mean, this is smooth,
0:13:07 > 0:13:10and on this side it's a very sandy feeling.
0:13:10 > 0:13:12A real magic ingredient,
0:13:12 > 0:13:17and quite sobering to think we didn't even get off step one today.
0:13:18 > 0:13:22Clearly, I wouldn't make a living from cannonballs.
0:13:22 > 0:13:25But then, the bottom fell out of the market a while ago.
0:13:27 > 0:13:30Early in the 19th century, plumbago from near here
0:13:30 > 0:13:34started to fall in value as other sources were discovered overseas.
0:13:34 > 0:13:39Local miners had to find new uses for their graphite, in other words plumbago,
0:13:39 > 0:13:42and turned it into pencil leads.
0:13:42 > 0:13:44Swords into plough shares.
0:13:44 > 0:13:45Cannonballs into pencils.