Towards the end of a production line deep inside a factory near Cardiff, two workers are almost halfway through their 120-hour shift. The grey and white ABB YuMi robots have torsos, shoulders, elbows and hands, and the physiques of heavyweight boxers. They have most weekends off, but when demand peaks, as it often does these days, they can work without pause, as human shifts come and go around them.

Hunched side by side over a conveyor belt, the robots pluck USB ports from small plastic palettes. With barely a whir, they move them to a second conveyor before pushing them into pinprick holes in green circuit boards. The parts will allow consumers to connect to and program the Raspberry Pi, Britain’s most popular – and smallest – computer. In the past five years, 10m of these credit card-sized PCs have been made here, in an old television factory in South Wales.

On the Raspberry Pi production line.

A third YuMi in the row is motionless and missing its hands. Engineers are adapting new grippers to allow it to attach a connector called a GPIO, which can link the Pi to other devices. In the meantime, a young technician called Lauren Yarde does the job. Wearing a white coat, the 20-year-old sits in line beside her headless colleagues, fixing the parts to the circuit boards. “I never thought I’d be working with robots,” she says, as computers slide between artificial and human hands. Does she feel part of a team? “Well, they can’t argue with you,” she says, smiling.

The “collaborative” robots, or “cobots”, are part of a new chapter in an unlikely British manufacturing success story. Sony arrived here in the mid-1970s, bringing jobs and hi-tech hope to a region built on coal and steel. At its peak in the 1990s, this factory, and its now shuttered sister site near Bridgend, employed more than 4,000 people and made 15,000 televisions a day. But in 2005, the flat screen shattered the cathode ray tube, and Sony moved its TV production to eastern Europe and Asia. Hundreds of workers lost their jobs.

Gareth Jones was among the survivors, and has worked under this roof for 30 years. The son of a Swansea steelworker now manages 500 employees, a number still growing despite the recent robot recruitment. Yarde will get work elsewhere in the factory, he says, because automation is helping Sony create more business, which means more jobs, most of which require human hands.

Occupying half its original site outside Pencoed, an old mining town, the Sony UK Technology Centre makes several products, including broadcast video cameras, streetlights for a Canadian company, and laser hair-removal devices for a Swansea firm in partnership with Braun. Contract manufacturing has allowed Sony to preserve and grow its expertise.

Schoolchildren get fed the story that we don’t make anything here any more, that manufacturing is dead

It is Jones’s job to bring in the new business. In 2012, he read a news report about the Pi, and problems with its production in China. Pi models range in price from just £5 to £30, and can be easily programmed to perform countless functions, controlling everything from digital signs to the lights in a connected home.

Eben Upton, a Welsh-born Cambridge University academic and businessman, expected to sell only 10,000 devices when he conceived the Raspberry Pi as a small, affordable computer that could be used to teach programming; he set up a foundation at the same time to promote education. He also assumed that only China could make them cheaply enough. Jones, an engineer by trade, saw that as a challenge. He invited Upton to South Wales and presented his calculations. Production started months later. Automation, as well as savings in shipping and logistics, means Pencoed is cheaper than Shenzhen would be. “That gives us a massive sense of pride,” says Jones, 58. “We’ve seen the other side of the coin here, the negative impact of a wave of production going out to the far east. Now we’re getting it back again.”

On the Raspberry Pi factory floor.

Jones keeps a steel ruler in the top pocket of his white coat, an old habit from his engineering days. “I still use it occasionally, but it’s also good for opening letters,” he says. “Reshoring”, as it’s known in the industry, or the return of production from other countries, means Sony is recruiting again locally, when 10 years ago the factory and Pencoed seemed doomed. It’s the reason Jones is passionate about British manufacturing, which he believes is misunderstood. “Schoolchildren get fed the story that we don’t make anything here any more, that manufacturing is dead,” he says. “Or if it’s not dead, it’s dirty, smelly, greasy.” He surveys a spotless, quiet scene of busy people and machines under bright lights. “When they come in here, they see what modern British manufacturing is really like.”

***

In the 1970s, manufacturing still accounted for 25% of the UK’s national income and 7m jobs. But after four decades of Margaret Thatcher’s reforms, New Labour’s “knowledge economy” and dizzying globalisation, only 2.7 million people make stuff today, accounting for 10% of national income. The world’s former workshop now ranks ninth as a producing nation, behind India, Italy and France. Now Brexit is convulsing the industry. Overall production has grown this year, to a 17-year high in the case of cars – partly because of a boost in exports triggered by the falling pound. But even the companies making hay today fear the long-term effects, putting the government under pressure to secure a good deal on trade and immigration.

As uncertainty builds against a backdrop of long-term decline, I set out on a journey covering 1,000 miles to visit five very different and very British production lines. In this global, digital, unpredictable age, what does it mean to be made in Britain?

***

Fiona Wright’s job at Alexandra Dock in Hull did not exist a year ago. After the dock’s completion in 1885, when Britain had enjoyed a century of industrial dominance, tonnes of Yorkshire coal were loaded on to ships here. Timber pit props from Scandinavia came the other way. The trade, as well as fishing and whaling before it, brought prosperity to a city brimming with jobs, grand architecture and civic pride. But as German bombs, North Sea fishing disputes and pit closures took their toll, Hull and its derelict docks became sorry bywords for Britain’s industrial decline.

Last year Siemens, the German industrial giant, opened a £310m wind turbine blade factory at Alexandra Dock, where the air was once thick with coal dust. Wright, the 25-year-old daughter of a Humberside bus driver, applied for one of 1,000 new jobs. She and shift manager Leigh Powell, 35, show me what it takes to build the giant blades for the North Sea’s mushrooming windfarms. The factory, a giant grey box, covers the area of about eight football pitches. It’s airy and almost feels empty, until a blade comes into view.

A technician at Siemens’ wind turbine plant in Hull. Photograph: Bloomberg via Getty Images

“You can’t really compute the scale of them until you’re standing next to them,” Wright says after I’ve had a health-and-safety briefing. Suspended on its side, a 75m blade – the length of a 747 airliner – is waiting to be rolled into a spray booth and painted white. Wright has helped to make it by hand, layering sheets of fibreglass and balsa wood blocks into a mould. Resin is then injected into the layers and the hollow blade is cured as one – the largest object cast as one piece anywhere in the world.

It is arrestingly beautiful; the jade translucence of the resin making it look like a giant of the deep. At the larger end, which will later be attached to the turbine itself, I step inside the circular opening. If Powell let me, I could walk farther inside without needing to duck my head for 30m or more. “You could actually drive a transit van in here,” Powell says, his voice bouncing towards the blade’s tip.

Outside, 80m steel cylindrical towers stand taller than any building in Hull. Soon, they will be floated out to Race Bank, a windfarm being built off the north Norfolk coast, and planted on foundations already laid on the shallow seabed. A nacelle, or turbine unit, is placed on top of each tower before the three blades are fitted. They are built to survive 20 years, and in North Sea storms their tips can flex along arcs of up to 25m.

In his old job, Powell helped maintain steam turbines for coal power stations, but he now sees a future in wind. Last year, wind generated more power in Britain than coal for the first time, or 11.5% of the total. Dong Energy, a Danish energy company ditching oil and gas for wind, predicts that proportion will rise to 50%. The company operates eight UK offshore windfarms, with seven more under construction or in development, including Race Bank. When they are all spinning, Dong Energy calculates that its turbines alone will generate enough electricity to power 8m British homes.

Siemens was one of the loudest corporate voices against Brexit. But Hull still voted 66% to leave

Employment in the sector is rising fast, reaching 117,000 in Britain in 2015, before the Hull plant opened. Wright, who left a job at Asda to work here, has already saved enough to buy her first house with her boyfriend. “And somebody got my job in the supermarket,” she says. “If you bring 1,000 jobs into a city that struggles with employment, it makes a world of difference.” Wright thinks the factory has also helped restore pride in the city. One of Siemens’ blades was recently displayed in Queen Victoria Square where, reinvented as an art installation to mark Hull’s year as UK City of Culture, it drew thousands of curious visitors. “My parents were gobsmacked,” Wright says. “They were looking for the seam, but the way we make them, there is no seam.”

Wright is full of optimism about the company’s future, and the city’s. “If we’re capable of making structures as beautiful as these, we must be good at something,” she says. “You can’t make these in London.”

But conversation soon turns to an issue dividing this area like so many others. During the EU referendum campaign, Siemens was one of the loudest corporate voices against Brexit. One of Europe’s largest manufacturers, the company employs 15,000 people in the UK, a third of them in manufacturing, and relies on free trade and movement of people. But its position was not enough to persuade Hull, where 66% of the city voted to leave. Wright wasn’t among them. “I think there’s definitely a generational gap,” she says as we leave the factory. “It’s the same with renewable energy: young people want to embrace it.”

***

There are mixed feelings about Brexit Britain in Plymouth, too, where the order book is overflowing at Princess Yachts. Founded in 1965, the company employs 2,300 local craftspeople to make just 280 boats a year. The luxury motor yachts – think Bentleys on sea – range in size from 12-40m, and from £500,000 to £17m or more. At prices like these, even a slight dip in the pound can mean big savings for foreign buyers, who make up as much as 90% of the clientele. After the company made losses and job cuts in 2015, orders are now at their highest for almost a decade, and the workforce is growing as the company sails back into profit.

At Devonport Dockyard, where Princess occupies a big chunk of Plymouth’s historic naval base, a helicopter has landed next to the slipway. Some of Britain’s great battleships were launched here after William of Orange ordered the construction of the dockyard in 1689. Today, gin palaces make the same entry into the Tamar, destined for the more peaceful waters of the Côte d’Azur and the Caribbean. The helicopter belongs to a prospective customer. But tides fall and Antony Sherriff, the executive chairman, is also cautious about a future trade deal. The fall in the pound is already working both ways: imported parts are more expensive. At the company’s biggest facility, two van-sized engines wait to be installed into a 40m hull. They are German, and cost £1m each.

Making checks on a wind turbine blade in Hull. Photograph: Bloomberg via Getty Images

We move to the Grade l-listed ropery, a long, narrow stone building originally built for the navy in the 1760s. Men with saws are building lifesize mock-ups of future yacht interiors in plywood and foam; no design is signed off before sightlines and layouts are reviewed at full scale. Next door, the old hangman’s cell, where French sailors met their end during the Napoleonic wars, has not been repurposed. “The irony is that the French now own it,” says Bill Barrow, Princess’s manager of international sales. In the luxury market, prestige brands still hold a potent allure among wealthy foreign buyers, both individual and corporate. In 2008, LVMH, the French luxury goods conglomerate behind brands including Louis Vuitton, as well as British names such as Thomas Pink and Glenmorangie, bought Princess Yachts for a reported £200m. If Siemens is banking on the growth of renewable energy while it weathers any Brexit storm, Princess is banking on the buoyancy of the British brand itself.

***

In a locker room on the outskirts of Guildford, I’m asked to put on a long blue coat, a hairnet, a beard cover and a pair of anti-static shoe covers. In space, hair is the enemy. The 500 employees at Surrey Satellite Technology Limited (SSTL) are discouraged from wearing shorts in the summer, lest leg hair find its way into the product, which can sell for up to £100m, including launch and operation. Only the Queen has been permitted to forgo the hairnet during her visits to the world’s leading small satellite factory.

Guildford emerged as a global space power largely thanks to one man. In the early 1980s, Martin – now Sir Martin – Sweeting, a scientist at the University of Surrey, persuaded Nasa to piggyback into space an amateur radio satellite he had developed. The timing was good. Space was beginning to open up after years of military control following the launch, 60 years ago this October, of the first satellite, the Russian Sputnik 1. The end of the cold war then triggered a second space race as companies emerged to build the ever smarter, smaller and more affordable satellites that sustain modern life. More than 1,300 now orbit Earth. Sweeting, who founded SSTL here in 1985 and remains the executive chairman, was poised to take advantage.

Sheathed in protective gear, Luis Gomes, a space scientist and the company’s commercial director, guides me into the assembly clean room, a cavernous space with brilliant white walls and a blue floor. Satellites in various states of completion range in size from large shoebox to small bathroom. SSTL has government and corporate customers all over the world, and is currently building 18 satellites for as little as £10m each. Some are for communications, others for navigation, mapping and imaging. Essentially space-borne telescopes fixed to digital camera sensors, the imaging craft send photos back to Earth to show the progress of forest fires or the level of reservoirs. Farmers with vast acreages can analyse the quality of new growth to precisely calculate eventual wheat yields. “From here, we could also map the entire globe every day,” Gomes says. “When I started 20 years ago, all of this was unimaginable.”

SSTL engineer Tom Boulton fine-tunes a satellite. Photograph: Ben Quinton for the Guardian

In an upstairs lab, Tom Boulton, an electronics engineer, demonstrates the reaction wheels that allow satellites to move within their orbits. “People imagine they have thrusters, but we have a very limited fuel supply,” he says. In low gravity, a wheel spinning inside a sealed drum the diameter of a side plate will, according to basic physics, rotate the object to which it is fixed the other way. Multiple wheels bolted on multiple planes, and powered by solar panels, allow for minute movements in any direction. Boulton punches numbers into his computer and the wheel on his workbench comes to life like a turbo-powered salad spinner, topping out at 5,000 revolutions a minute.

In 2008, SSTL’s reputation resulted in a buyout by the French aerospace giant EADS Astrium, now Airbus, for a reported £40-50m. The company employs scientists and technicians from 20 countries. Here, too, the B word hangs in the air. Gomes, who is 45, started working here 20 years ago as a physics graduate from the University of Lisbon in Portugal. “Sixteen percent of our staff are from the EU, and obviously I know that number well at the moment,” he says. Across the academic and technology sectors, there is concern not just about what Brexit will mean for the cost of imported parts and access to markets, but also the supply of brains. “People still want to work here, but of course they will start thinking twice at some point about how secure it is for their future,” Gomes says. There are further, big questions about Britain’s ongoing role in Galileo, the EU’s new precision navigation system, for which SSTL is building several satellites.

Publicly at least, Gomes, like Jones, Wright and Powell, is confident that the high demand for what he makes will ensure his company weathers Brexit. He is already racing to meet the needs of the next era: for faster internet, driverless cars, pilotless planes and ever sharper imaging, all of which will require us to fire more sophisticated computers into space.

***

I end my journey firmly on Earth, in a garden shed in east London. Hardev “Pops” Singh Sahota is trying to remember the original recipe for his hot sauce. He pulls out a tattered old box containing Tesco-branded kitchen scales and places it on a workbench. The shelves above it carry plastic tubs of spices and powders. Singh, 62, who wears double denim and a black turban, is joined by his wife, Kamal, and eldest son, Kuldip, 35. They all live in the terrace house at the other end of the garden, an unlikely base for a British brand now stocked by Selfridges, Budgens, Asda, Ocado and beyond.

Lifting the lid of the box, Singh Sr reveals an old Post-it note barely clinging to the cardboard. “This was the first time I wrote it down,” he says of the recipe he developed here in the 1980s to satisfy his taste for hot food. He has agreed to make a special batch today. The family have already picked the stalks from bird’s-eye chillies. Singh adds the other ingredients to the pan: chopped tomatoes, malt vinegar, salt, dark soy sauce and brown sugar.

When my dad cooked, he said, ‘If water is not running out of your nose, the food is not good'

“Pops”, as his three sons call him, grew up in Kenya, where his own father and uncle, both watchmakers, had emigrated as young men from the Punjab. In Kenya, Indian immigrants developed their own cuisine, gathering outside for large, slow, boozy barbecues known as karogas. Spices featured heavily. “When my dad cooked, he said, ‘If water is not running out of your nose, the food is not good,’ ” Singh recalls. When the family resettled in Britain in the 1970s, where Singh went to university and became a design and technology teacher, they continued the tradition. Singh took on weekend barbecuing duties and, after full days at his school in Harrow, he cooked late into the night at a local Indian club.

He traces his ambition to a moment when, aged about five, he saw his father praise another man’s son. “I don’t know why, but it came to my heart and stuck there,” he recalls. “I wanted to be that boy one day. But I didn’t know if I was going to get it.” He tried food trucks before they became a city centre staple, and sold a few bottles of his sauce in local stores. As he toiled, he felt like a stranger to his sons. “He never explained what he was trying to achieve, so we only saw the hardships and the friction it caused,” Kuldip says. “We didn’t know him.”

Kuldip, meanwhile, was himself flitting between career paths, from fashion and then furniture marketing to estate agency and property development. But when he spotted an advert for the 2008 BBC Good Food Show in west London, he reserved a stall using his credit card. The family had a week to make and label 1,000 bottles of hot sauce, forming a production line in the shed and garden, eyes red with chilli fumes. “When we drove to the show at 6am, some of the bottles were still warm,” Kuldip recalls.

‘Pops’ Sahota with wife Kamal and son Kuldip, making Mr Singh’s sauces. Photograph: Ben Quinton for the Guardian

The sauce sold out and a new British manufacturer was born. Almost 10 years later, after a slow start, some brushes with disaster and a successful round of crowdfunding, Kuldip and his father have turned a culinary heritage and a modest recipe into a thriving business. Demand quickly consumed their shed; a contract manufacturer in Cambridge now produces more than 100,000 bottles of Mr Singh’s sauces a year. A range of crisps is on the way, the spice mix having been perfected in the shed. Most days, father and son travel to company HQ, the former shop in nearby Plaistow where Kuldip’s grandfather repaired watches. He died five years ago, but Kuldip’s grandmother, who is in her 80s, still lives there and cooks lunch for the team every day.

As a teenager, Kuldip’s brother Rav, 31, used the garden shed to DJ and MC. He now makes music videos to promote the sauce, starring his dad, which have had more than 1m views on the company’s Facebook page. They include Fresh Prince Of Chilli Sauce (“In east Africa born and raised/On the barbecue’s where I spent most of my days”) and Hotline Singh. Spice Boys, a version of Wannabe by the Spice Girls, earned the family a live Skype interview on one of Chicago’s biggest news shows. There are now plans to export to the city, as well as to France, Hungary and even India. To Pops Singh’s delight, he has already cracked Kenya. “And everything is made in Britain,” Kuldip says. “The bottles, the ingredients: all packed here, traded in pounds and shipped to Kenya, building the brand.”

The Sahotas plan to keep growing, following a route familiar to homespun British food brands, including Tyrrells crisps and Levi Roots’ Reggae Reggae Sauce. Their product shares little DNA with wind turbines, satellites, boats and computers, but the family show the same cautious but irrepressible optimism I have seen across the country. We make less in Britain than we used to, but the pride and expertise poured into each product appears undimmed.

In east London, manufacturing has also united a family. In the house, where today’s one-off batch now sits in bottles, a threatening red, Kamal has prepared lunch. She does not like spicy food, so a bottle of (optional) sauce sits on the table. It is fiery yet not overpowering, a precision-guided chilli kick. Sure enough, my nose begins to stream. “This is where I wanted to get to in my life,” Singh says, reflecting on his long search for success. “I just didn’t know how at the start. And it feels fantastic.”

Best of British: stuff we still make

Photograph: Graham Seager

Ercol In the late 19th century, High Wycombe’s furniture factories knocked out 5,000 chairs a day. Few survive, but premium maker Ercol, founded in the Buckinghamshire market town in 1920 by Tuscan joiner Lucian Ercolani, still flies the flag – now in nearby Princes Risborough.

Photograph: Alamy

Merrythought Britain didn’t invent teddies, but made them by the million in the 20th century, in more than 30 factories. Merrythought, founded in Shropshire in 1930, is the last one standing. Now run by a fourth generation of the Holmes family, it made the official 2012 Olympics bear and has a cult following in Japan.

New Balance and Dr Martens Founded by a Brit in America in 1906, Boston-based New Balance began manufacturing in a redundant shoe factory in Cumbria in 1982, where it now makes almost half a million premium ‘Made in the UK’ pairs in leather each year. Meanwhile, Dr Martens has revived limited shoemaking at its old Northamptonshire factory, after moving production to the far east in 2003.

John Smedley The original longjohn maker claims to operate in the world’s oldest working factory, a 1784 cotton mill in Derbyshire built by the first John Smedley. His son, also John, switched to wool, and the family firm still makes designer knitwear. Customers have included Audrey Hepburn, the Beatles and the Queen.

Cello Electronics Cheap labour in Asia all but killed electronics manufacturing in Britain – Sony alone used to make 15,000 TVs a day in the mid-1990s – but one company holds out: Cello Electronics, established in 2001, make more than 300,000 flatscreen TVs in an old carpet warehouse in County Durham.

Photograph: Alamy

Brompton In 1976, landscape gardener Andrew Ritchie designed a fold-up bike in his flat overlooking Brompton Oratory, a west London church. Still based in the capital, Brompton makes around 50,000 bikes a year, 80% of them sold overseas, and is one of the last major cycle manufacturers in Britain.