Born in 1970 Joseph Fiennes is the youngest brother of actor Ralph, film makers Sophie and Martha and composer Magnus. His twin Jacob is a conservationist. On leaving art school he trained at the Young Vic. His latest film, Running With Scissors, is released next month

You picture Joseph Fiennes brandishing a quill, but off screen the Shakespeare in Love actor is more likely to be working the throttle of his beloved Triumph Scrambler. Less gentleman of Verona than of Va-rooma.

Fiennes, the youngest of six children including his actor brother Ralph, fell in love with motorbikes aged 16. "My first was a red Honda 125 nicknamed the Red Peril because I kept coming off," he laughs. "I was living in Suffolk and used it to go to art school. Whenever you went low round a corner the footrest would hit the ground. Still, it was better than catching the train."

Fiennes does not strut or swagger - he is too shy for that - but everyone in the west London members' club where we meet looks up when he enters. With his deep brown eyes he looks to be deeply troubled, a gift to casting directors. He is casually dressed in a brown shirt undone enough to display manly chest hair, to the thinly disguised sniggers of Notting Hill's trendies taking late-morning wake-me-up black coffee.

Although Fiennes often plays historical, cultivated and rather tortured roles he is racier than you might imagine. He is an accomplished swimmer, tennis player and rock climber and not averse to more high-octane thrills such as blasting round the Millbrook racetrack in a Jaguar XKR that he once owned.

"It is banked in a bowl and I did 170mph and was still passed by these little supercharged Nissans that were doing trial tests," he says, shaking his head, sipping mineral water. "I would love to know what they had in their tanks."

You see two sides to his personality when, within minutes of our meeting, he launches into a long speech about the environment. "Our generation has to take on the weight of the damage they are doing to the environment but I do believe greenies and petrolheads have to work together," he says. "I love my Triumph (provided by the company) and the open road, but I am hugely aware of the damage it causes."

His attempt at saving the planet by taking up bicycling was shortlived, however. "I was hit by a double-decker bus," he reports. "I stopped for a lady crossing the road and the bus carried on - forcing my saddle into my spine." Ouch. "It was very painful, so I went back on the Tube."

After a peripatetic childhood Fiennes abandoned plans to become a painter and followed his brother into acting. He had a rough time being dismissed as Ralph's little brother, but has more than stepped out of the shadow. The turning point was 1998's Shakespeare in Love, in which Gwyneth Paltrow bagged an Oscar playing opposite his Will Shakespeare.

He has also starred in The Merchant of Venice and Elizabeth. His forthcoming cinematic vehicle is more modern. Running With Scissors is about a boy's struggle for survival after he is adopted by a dysfunctional 1970s family.

"I try to mix my work," says Fiennes. "I was in the West End for five months last year. I am lucky to have a great balance." So he means he can do serious work, then cash in with the odd Hollywood blockbuster? "Not always," he laughs sardonically. "Some obscure film work can pay even worse than theatre. There are a lot of actors struggling to feed and clothe their families." Not that Fiennes seems overly fussed about dosh: he turned down the starring role in The Pianist, whose leading man went on to win an Oscar, so he could honour a theatrical commitment.

"There are great creative choices outside the mainstream. I would like to do more experimental films, rather than Dukes of Hazzard 5."

A quietly amusing man, Fiennes recalls an LA casting agent telling him that he 'loved' his work. What, inquired our man proudly, had the agent seen him in? "Nothing," came back the deadpan reply, devoid of either irony or awkwardness.

As well as his love of motorbikes Fiennes has also enjoyed dalliances with cars. "When I'm doing theatre with the RSC (in Stratford-upon-Avon) I drive. I've had an array of cars, most not very glamorous - hatchback thingies." This isn't entirely true. As well as the XKR his stable has included an Audi TT and currently a Range Rover Sport.

But bikes remain his greatest passion and he recently road-tested the new £7,199 Triumph Daytona 675 Triple: "It was a whole other experience. If you like g-force and your cheeks flapping in the wind, that's your vehicle - beautiful, thrilling, it took me into another world." His eyes glaze over at the memory.

Still, for everyday use round London he sounds more than happy with his less nerve-jangling £5,899 Triumph Scrambler. "It keeps going in all weathers and there's a good bit of torque there."

The only problem is finding a parking bay for it - he was forced to return home with the bike and walk back to our interview after failing to find a spot. "It's the bane of my life and seems intentional," he says. "I don't understand why: after all, bikes have much smaller engines than cars."

And with that he saunters home to retrieve his bike, leaving several women at the bar more than a little in love.

On his CD changer

Massive Attack, Collected; Cody Chesnutt, The Headphone Masterpiece; anything played by violinist Viktoria Mullova