Q: In Rancid Aluminium, you play a psychotic but well-dressed accountant: why is it that accountants get all the best clobber?

J: I think it's a mixture of vanity and the need to get respect when you're powerful. My character in the film is a bit of a monster - ambition gets the better of him. You hardly notice it, but he changes his watch at the end so it's got a gold instead of a leather strap, and the suit's a Marks and Spencer one at the beginning but Armani at the end.

Q: Were you relieved not to be wearing tights again after Elizabeth and Shakespeare in Love?

J: Well, after Shakespeare, I did a modern play where the costumes were great: sharp suits in bright spangly colours like mauve, red and green. But I love the Elizabethan age. It was hugely imaginative in terms of clothing for men. Things like the codpiece and huge puffy breeches were worn by Henry VIII as a sign of masculinity. The ruffs are wonderful as well - they really do change your posture, make you strut around like a peacock.

Q: Are you very vain about your work wardrobe?

J: Acting is such a collaborative process that, in the early days, when a designer says you have to be naked and covered in blue paint, you accept it. But, as you grow older, you start saying, "No, sorry. I don't want to humiliate myself again." The worst experience I had was wearing a jockstrap and not much else for Troilus and Cressida at the Royal Shakespeare Company - very uncomfy, and it doesn't help the voice, either.

Q: Today you're sporting quite a bit of stubble: are you a fan of facial hair?

J: Well, I'm lazy about shaving. It's so boring. I've just come back from India and some of the facial hair there is incredible - big moustaches that are waxed at the ends. I like beards.

Q: At the Shakespeare in Love premiere, there was a rumpus over you supposedly wearing an outfit you bought from a charity shop? Were you really wearing second-hand togs?

J: No. It was just a stupid, flippant remark I made because I'm not used to premieres and being asked what I'm wearing. I take a lot of my old stuff to the local charity shop so, after the tenth time of asking, I said, "Oh, I bought it at the Notting Hill Housing Trust shop." And The Sun picked it up. I was amazed. It was actually Armani or something. Anyway, it was good publicity for the charity shop.

Q: As a kid, did you ever have to wear hand-me-downs from older brother Ralph?

J: Oh yeah. That's part and parcel of being the youngest. There were seven of us, so I always had a good pick. Although I didn't wear my sisters' clothes - it was a bit early to cross-dress. It was all practical gear because we led an outdoor life.

Q: You also did a turn as a Marks and Spencer model at one time: how did you get that job?

J: I didn't model for them in a whole campaign. It was a one-off shoot for an in-house magazine. The job came through a friend when I was at drama school. I needed the money to go towards rent and fees.

Q: Do you wear M&S clothes now?

J: No, I don't.

Q: when a woman drags you out shopping, do you help her choose her clothes or do you wander off and tell her you'll "meet her in electricals"?

J: If she's in need of assistance, then I'll help out - to the bitter end.

Q: Are you a shopaholic yourself?

J: No - I do enjoy shopping for clothes, but there's a limit. I like to go out on long walkabouts, so when I'm buying clothes, I'll take time to choose a good jumper and a comfy pair of boots to survive six-hour treks.

Q: What has been your biggest-ever fashion mistake?

J: I insisted on a clean white shirt every day when I was twelve. Is that a mistake? I suppose when you wear green spangly suits and puffy pants for work, you don't worry about fashion mistakes in real life.

Q: When you were a student actor, you worked as a dresser at the National Theatre. Were you at the sharp end of stressed luvvies' tantrums?

J: Well, some of the actors I've worked with since don't remember that I dressed them in those days. So, when I go to rehearsals, I go, "Yeah, you never tipped me and your pants were filthy." There was one quick change when an actor had to walk off, turn round and walk back on again in a different outfit. That was all slapped on in a second with elastic and Velcro - even the shoes.