THINGS to pack for an interview: microphone, batteries and tape. Things to add if you are interviewing Eddie Izzard: a lipgloss with a wonder-formula lip-plumping effect. Just a precaution, you understand.

Who doesn’t like Eddie Izzard? He appeals to so many different minorities - men, women, cross-dressers, jam-lovers and people who think they can still speak French. But talking to Eddie Izzard, well that’s a minefield.

Will we have to discuss the euro, for instance? Izzard is an enthusiast but for me it’s like having to listen to a talk on postage stamps or steam trains. And then there is his stand-up comedy; once it was a glorious thing, as videos like Glorious attest, but last year’s offering Circle was disappointingly lethargic, covering not one inch of new thematic ground, and coasting on Izzard’s likeability.

And then there is the issue of women’s clothes, a brave but baffling area of his life. For a long time, he seemed to favour dramatic black eyeliner, leggings, fitted jackets and stilettos which made him look like a 1982 Stars in Their Eyes Regional Winner version of Judy Garland. Last time I saw him live, things had got even worse with a long period dress with a bustle that recalled the late Queen Mary, both the royal and the luxury liner. With so much to talk about and yet so much to avoid, it seems prudent to pack lippy as a peace offering.

In fact, Izzard is rather bloke-ily dressed, in a black t-shirt, denim jacket and a kilt in the Baird tartan. Since there is no clan Izzard, he has opted for Baird "because it works colour wise".

To my relief, he doesn’t want to proselytise on behalf of the euro anymore either - or at least, not in depth. "I find economics incredibly interesting, but it’s shop talk really - like saying ‘country X, wow, the GDP!’"

On stage, Izzard is bold and witty with a charisma that draws in audiences, like one of those primitive forcefields in an early episode of Star Trek. Off stage, he is more reserved. He still rambles a bit, noodling into digressions and cadenzas like a jazz musician but he is more emotionally guarded one-on-one. He knows not to give away anything too precious.

He’d rather talk about weight, which he battles "by not eating anything really". He doesn’t much care for the gym, even though he describes himself as an "action transvestite".

There you go. I swear I wasn’t going to ask him about women’s clothing. He brought it up first.

When Izzard was growing up, he wanted to look like Raquel Welch during her bra-busting phase in One Million Years BC; failing that he would have settled for Diana Rigg during her Avengers period. Being a transvestite seems to mean he is interested in the external elements of femininity. He is interested in clothes and make-up. And he wouldn’t mind looking like a woman except his body lets him down rather there, with his footballer’s legs. And he gets tired of people assuming it’s some sort of gimmick.

"Someone wrote that my career wasn’t doing great until I was a transvestite," he says. "That pisses me off greatly." Especially since not everyone looks at a bloke in a dress and offers them a three-month run in the West End.

Once he was followed down the street at night by a gang of kids asking, "Why are you dressed as a girl?" and, instead of panicking, he turned round and said, "All right - I’ll tell you," and they all ran away.

"You disarm people by saying, ‘yes I’m a bloke in a dress’, because where can the repartee go from there?"

"I’ve been in one situation where I had one guy trying to beat me up and another one trying to get my autograph. The fight itself was a bit ineffective. It probably lasted about 30 seconds - because these fights seem to last for ages with this one guy going, ‘You gay twat’ and his friend going, ‘Wow, you’re Eddie Izzard’. Meanwhile, I’m trying all this point of order stuff. ‘No, I’m a transvestite, you really should get your slander correct.’ I have thought about finding out more about self defence though. I should be Tough Transvestite Who Can Take Care of Himself."

He started wearing make-up, and shoplifting lipstick, in his teens, when he simultaneously abandoned his early ambition to join the army ("there’s not a lot of make-up in the army - they’ve only got that night look, and it’s a bit slapdash, isn’t it?").

He is not gay although he quite likes the idea of being attracted to men, and his transvestism does not put off women. Quite the opposite. A friend of mine was chatted up by Eddie on a plane from Edinburgh to Heathrow, and wound up in the Met Bar in the wee hours of the morning, swapping make-up tips and phone numbers.

Eddie’s mother died when he was six, so, as he has noted in the past, there wasn’t much access to women’s clothes at home. Later he asked for psychiatric help, but his GP never came up with an appointment. And at this point I realise we have talked far too much about women’s clothes, and wonder why he needs to discuss the topic so much (an S&M fan rarely feels compelled to tell us where he buys his cleats and clamps). By now, surely, having to explain and defend transvestism must be something of a millstone.

"There was no way I could talk about it without it becoming a potential millstone," he agrees, "but it’s something that’s going to be there until other people come out. Then it will be, ‘Oh, he’s one of the eight million transvestites to come out, let’s go talk to the others’. Or ‘Let’s not talk to any of them’. Because you don’t go ‘Samuel L Jackson, you’re heterosexual, what’s it like?’"

Indeed - but if there are other TVs in the entertainment business, they aren’t exactly rushing forward to make a Spartacus-style declaration.

"Well I’ve seen Sam L Jackson in a kilt but he’s obviously straight. But there are some people you look at and think maybe they’re TV but they won’t say it because the image is so difficult to deal with."

Even without the dresses, Izzard is a comedy phenomenon. A little over a decade ago, he was doing 20-minute sets at the Fringe. Now he sells out theatres here and in America. He is the most popular British comedy stage act since the heyday of the Pythons and Peter Cook and Dudley Moore, with ruminations on cats that drill for oil and Jesus’ followers mulling over the crucifixion: "All the disciples, they’re saying, ‘He’s dead. Our leader is dead. How will we remember this day?’... ‘Well, uh, I was thinking... chocolate eggs’."

Famously, he refuses to do his stand-up act on TV - although this is not strictly true; you can catch snatches of it when he does chat shows and walloping great hours of it when his company sells shows like Glorious or Definite Article to Channel Four. On the other hand, he resists other easier commercial avenues - he doesn’t sell mobile phones like comedians Ed Byrne and Paul Merton, or banks like Alan Davies, or a beer he doesn’t drink like Jack Dee. Nor does he do corporate gigs.

He does wilder things like learn enough French to address comedy audiences in Paris on his favoured topics - "Je suis une travestie. En anglais, c’est a dire je suis une catastrophe" - and his English act includes a surreal routine about trying to make his way round France armed only with the words "Mon singe est dans l’arbre" ("My monkey is in the tree").

Judging from his conversation, his deceptively shambolic stage monologues are actually carefully rehearsed, if not scripted (he is "mildly dyslexic", and hopeless in print, spelling ‘marriage’ as ‘marige’ because "what more do you need?")

But now he is keen to branch out from stand-up. As Billy Connolly, Jack Dee, Robbie Coltrane and others have discovered, a performer cannot live by comedy alone and Izzard is focusing more on straight acting, channelling himself from loose, apparently improvised comedy to drama with the intensity of the clown who longs to play Hamlet.

This is not a recent whim; in fact he says he did not want to be a comedian in the first place and one of the reasons he has kept away from television is to preserve an anonymity he can exploit in drama. Izzard admits that he has had a career plan since he was 18, and in much the same way that he couldn’t pass for a woman, there’s an unspoken recognition that he does not have a leading man’s face.

Time and again he has been cast as the heavy in ill-fated films such as Circus, Mystery Men and The Avengers. Channel 4’s upcoming drama series 40 may change that - he plays a flash character called Ralphie who charms women - and his new film The Revenger’s Tragedy is a vast improvement on previous outings. As Lussurioso, he is remarkably at ease with restoration text reset in a fanciful designer wasteland that Izzard dubs "post-apocalyptic Oxfam".

He has paid his dues, he said, and has focussed on extracting the positive from each experience, even The Avengers, a film that should deservedly be kept in a kennel.

"It looked great and working with Sean Connery was great. In the end I’m just chewing gum and hitting people though and I don’t say anything. Even the ‘oh f***’ my bad guy says at the end was dubbed on by someone else.

"You have to be good enough to get the part, then big enough to practice and get better. I’m not naturally good at anything but I learn by constantly doing it and eventually something clicks. I will constantly learn and adjust. I’m so hungry to do good after the years where I wasn’t getting anywhere."

As the henchman in The Avengers, the costumes were regrettably blokey he says, although he kept his nail polish on underneath his character’s gloves. Connery spotted the polish one day and did a beautiful double-take.

Disappointingly, though, Connery appears to have expressed little interest in cross-dressing. Nor did he pick up on Izzard’s Connery impression, perfected in his early Edinburgh days: "I did it for him once and he didn’t recognise himself at all. He just kept saying, ‘Sho, when are you going to do theeshe impreshions?’"

As he gets ready to go, he gathers up his kilt carefully in order to raise himself elegantly from his chair, then points out his skean dhu.

"Do you know what skean dhu means? Knife. And do you know what sporran means?" he asks, and pauses impressively. "Purse.

"I rather like that. Somehow I don’t think many Scotsmen would be happy to think they were guys going around carrying a purse. You see, there’s more TVs around than you think."

40 begins on Channel Four in March