Undercover transvestite

The Big Interview: Eddie Izzard bounds into the room bristling with energy, as if he hadn't just walked up the steep, steep hill to the hotel lounge where we're meeting for a chat.

I had made the journey up in a shuttle - not the space kind, sadly, although we aspired to similar altitudes - and as we drove we'd passed a handful of over-optimistic mountaineers, sprawled out on the side of the way, gasping for breath as they tried to flag us down. Eddie is bemused when I tell him this.

"But that was nothing at all," he exclaims reprovingly.

No, it wouldn't be. Not to a man who can saunter insouciantly, hurtle relentlessly and wax his way lyrically through a three-hour gig (or longer) every night he's on tour; nudging, bewildering and charming his audience every step of the way.

Not to a man who can wake up one morning and decide to run a marathon, and then another marathon the next day, and the day after that. And the next day, and so on until he's run 43 marathons in 51 days.

Which he did. Last year.

And, of course, a simple stroll up the hill is but the work of a moment for a card-carrying action transvestite: running, jumping, climbing trees - and still putting on make-up when he gets there.

"Yes, still a transvestite," he nods. "Have been since I was four years old - although I am in boy mode for this tour.

"Some people seem to feel the make-up and the dress are fused with the comedy, and they're not. When I first started doing stand-up I was just, you know, in blokey mode - I'd already come out to the people I knew, and then, yes, later to the media. But they didn't believe me at first so I wore a dress at a gig and they said, okay we believe you now, and that was that. So it happened in stages.

"But then when I went to the States I did it all in one go, and they associated it with the comedy, thinking this was drag, but it isn't - drag is all about being in costume. I'm not wearing a costume, it's just the clothes that I've bought.

"Next tour I could be in girl mode, or it could be boy mode again. It's one's individual right to wear whatever one likes!"

Eddie Izzard, then, is a man who does whatever he wants. And what he does, he does brilliantly, exceptionally, testing whatever limits he comes up against, be they physical confrontations with brekers who challenge his mascara in the street (there was a punch-up) or flirting with the limits of his own willpower: forty-three marathons in 51 days - seriously?

"I wanted to do something that was going to be a massive boot-camp/healthy kick-start thing," he says. "I wasn't initially going to it with Sport Relief - which is linked to the Comic Relief charity - but then they sent out this letter saying, does anyone want to do anything sporty? So I thought, maybe I can do something with them - they probably know doctors who can test me out and that sort of thing - and of course it raises money . and it's an adventure!

"And then I am this determined idiot, a sort of relentless fool who will keep pushing away until things work, which you know, does help if you're trying to have a career. Or run 43 marathons. Determination's key. "Nelson Mandela!" Eddie lights up. "Now he was a very determined person with a big heart: 27 years in prison; comes out without any bitterness. Unheard of! "

But Eddie clearly did hear, and it was because of Nelson Mandela that he has come at last to South Africa.

Initially, Eddie says, he simply wanted to do a few gigs and then give all the money they made to Nelson Mandela.

"I'd have been happy to hand it all over to him, actually, but he has three charities so I thought we'd do this with 46664 - it seemed it would be a great way to arrive in South Africa."

Later, on stage, Eddie Izzard is gaspingly funny. He claims to be jet-lagged - he's just flown in from a superbly successful run of shows in the US, where he was the first non-American comedian to play Madison Square Garden - but his energy is boundless, and he's clearly enjoying the show as much as the audience.

His seemingly random stream of consciousness takes in, as he describes it, the entire history of "everything that's ever happened - with gaps" and introduces such obviously logical insanities as jazzed chickens (donkey on snare, cue sultry hip wiggle), to wikipedionics, stone age transvestitism, literary squids, tapestry-weaving paparazzi at the battle of Hastings, God, Noah, giraffes, squirrels, Moses and God (more God).

No soot. There was no soot mentioned. In any way. I would have noticed. There was, however, a surprising, fleeting, blink-and-you-miss-it mention of Henry VIII and a certain president in the same breath.

I get the feeling he's surprised by how good a time he's having in South Africa. This is his first visit, after all, and how was he to know what a following he had here?

But his shows have sold out; steep ticket prices deterring exactly none of us - what better cause could you possibly imagine, after all, than a Nelson Mandela charity?

At the end of our interview, we chat about his recent work in front of the camera - The Riches TV show, which he remains hopeful will return as a feature film, and his most recent stint as the sociopath Torrence in the BBC's Day of the Triffids.

These, and his rich cinematic career (The Cat's Meow, Shadow of the Vampire, Oceans 12 & 13, Valkyrie and much more) are required viewing, but for the true Eddie Izzard fan, his appeal is down to nothing more - or less - than his warm, stripped down, gloriously relentless, dressed to kill, unrepeatable self.

Good to see you, Eddie. Now don't be a stranger.