How did an old-fashioned British manufacturer of motorbike clobber become the label of choice for the Hollywood set?

Longton, Staffordshire, is one of the original six Potteries towns that make up the city of Stoke-on-Trent, where it is known, rather disparagingly, as "the neck end". Once home to so many "bottle-oven" brick kilns that the streets were clogged with the fug of chimney smoke, Longton now fights urban decay. There's no obvious connection to the red carpets of film premieres, to nation builders and iconic revolutionaries, to pioneers of aviation or heroes of motorsport.

Yet it has all of those associations because of Belstaff, the eminently practical 85-year-old British clothing brand that has recently sewn up the market in dressing Hollywood stars. Daniel Radcliffe appeared in a specially made Belstaff "Harry Blouson" in Harry Potter and the Half-Blood Prince, Hilary Swank was clad in a brown Belstaff leather to play American pilot Amelia Earhart in Amelia, and the same label was used to clothe Aaron Johnson as he portrayed a young John Lennon in Sam Taylor-Wood's Nowhere Boy. Tom Cruise wore Belstaff in Mission Impossible 3, as did Will Smith in I Am Legend, Cate Blanchett in I'm Not There, Johnny Depp in Sweeney Todd and Brad Pitt in The Curious Case of Benjamin Button. George Clooney and Angelina Jolie are among those who choose to dress in Belstaff while not on the set.

The company's ambition extends beyond mere terrestrial stars. Richard Branson will don a specially-made Belstaff jacket aboard Virgin Galactic on its inaugural space flight in 2011. The white parka coat that will keep warm Pope Benedict XVI during winter walks in the Vatican garden carries the discreet but distinctive wreath logo of this same British brand.

All this has its roots in Longton, where Harry Grosberg founded a waterproof coat manufacturer in 1924 with his father-in-law Eli Belovitch. The company name fused Eli's surname with the Midlands county where the factory was based.

Yet as much as Belstaff clothing rejoices in its origins, with all garments carrying a union-flag tag, this is also an Italian success story. It is a cross-cultural love affair that is well reflected in the new film Nine (an adaptation of Federico Fellini's 8), which pays homage to classic Italian style but features great British actors such as Daniel Day-Lewis and Judi Dench. The sharp Sixties Italian suits are made by Belstaff, a label that once kitted out Lawrence of Arabia and still sources fabrics from the British Millerain Co Ltd, suppliers to the British Army for more than a century.

Movies are in the blood of the Malenotti family, which now runs Belstaff. Grandfather Maleno Malenotti was an acclaimed film producer, a Cinema Italiano contemporary of Fellini's. Maleno's son Franco was a motorcycle designer and champion rider who developed an obsession with a brand of coat made in Stoke-on-Trent from fine Egyptian cotton waxed with natural oils, the adopted uniform of flyers and bikers. After being invited to work for the company as a designer in 1986, he rescued the name when the business fell into financial difficulties and lovingly rebuilt it outside of Venice. Franco's own son Manuele is now the CEO of Belstaff and has squared the circle, combining the glamour of the film world with the style of those early-20th-century speed-seekers.

In London for the recent premiere of Nowhere Boy, Manuele explains the company strategy over breakfast in The Dorchester hotel. "All the clothes that you see on the big screen are available in our stores and this is something new in the world of fashion. Everybody has the possibility of dressing like a hero, like John Lennon or like Tom Cruise as Agent Ethan Hunt in Mission Impossible or Johnny Depp in Public Enemies," he says.

A trained lawyer, Malenotti has become a specialist marketer. The attraction of Belstaff clothing is rooted in the "protection and functionality" linked to its early associations with motorcycling and aviation. "Today it's more important for people to have protective and functional clothing because everybody is moving faster and travelling more," he says, his sales pitch propelled by three shots of espresso. "The internet democracy has made everyone an adventurer."

Not even Giorgio Armani, he argues, has been so successful in partnering with Hollywood. There is much competition, he acknowledges. "Now that there is a big [economic] crisis, and conventional advertising doesn't work as before, the fashion labels are looking for something new and the movie idea works."

But a presence on screen can't be bought. "That's not possible because you have to pass through the costume designer and they are superstars. Even the producer cannot tell them what to do," says Malenotti, citing collaborations with Sandy Powell (Aviator) and Colleen Atwood (Mission Impossible). The costume designer is only one hurdle. Belstaff has needed to get the nod from "the biggest directors... Steven Spielberg, David Fincher, Martin Scorsese," he says. "They need to say, 'Yes, they look great on camera'."

The studios get more out of the relationship than just the clothes, he claims. "Big Hollywood companies like Sony, Warner, Universal and Fox, love to collaborate with us because we make the movie look better but also because we create a global strategy to promote the movie with them." Nine will benefit from Belstaff commercials themed to Cinema Italiano. Amelia will launch with Swank's Belstaff Amelia Bomber in the windows of the company's 20 prime-location stores.

Belstaff, which has outlets in London, Manchester and Glasgow, claims to be bucking the recession and is extending its territory beyond the motorcycling tradition that drew Che Guevara to its clothing when he rode around South America in 1951. It is sponsoring sailing, styling cars for Audi, bringing out ranges of underwear and watches. "It started as a brand that was dedicated to motorcycles and aviation and has now become a lifestyle brand," says Malenotti, who has 15 motorcycles himself because "it's the only way to get around if you don't want to spend all day in the car". In reality, there are many Belstaff brands, from the Trialmaster, favoured by the most iconic motorcycling film star of them all, Steve McQueen, to the classic Sixties Roadmaster and the Panther, worn by Brad Pitt as Benjamin Button.

A new design emerged in November, the Peace jacket, commemorating the fall of the Berlin Wall and presented to such Nobel Prize winners as Mikhail Gorbachev and FW De Klerk during an event in Germany organised by Malenotti and his younger brother and colleague Michele. The one garment that will probably never go on wider sale is the Pope's parka, for which the Bishop of Rome had three fittings. "It's made with a very soft cotton, which we developed just for him, with a white corduroy collar and cuffs. He wears it when he goes to the mountains and every day he walks in the garden of the Vatican."

For Malenotti's father Maleno, the story has transcended any movie script. "My father is an incredible lover of the motorcycle world, all his life. When he rode by motorcycle from Italy to London he would be wearing Belstaff and all his friends would say, 'Bring me a Belstaff'. It was the only thing to wear if you wanted to feel cool in the Sixties," says his eldest son. "He was so proud to collaborate with such a historical name and when the factory in Stoke-on-Trent was having problems he decided to move the production to Italy and saved the brand. For him it's like his baby."