PAUL'S 20 MINUTES OF FAME; Quick-thinking Merton has just moments to prepare improv gig before hitting stage.
As the Edinburgh Festival Fringe gets underway, the city is creaking with performers who have pushed themselves to their limits searching for perfection.
They've put their lives on hold, written and rewritten their material and rehearsed it to exhaustion.
Paul Merton, on the other hand, is just turning up.
He has no idea what he or any of his troupe of Impro Chums will do when they step on stage and face their audience in the Pleasance at the end of this week - nor is he expecting inspiration to strike anytime soon.
There's no need to panic, though. As he cheerfully points out, there's plenty of time. He only needs 20 minutes.
He said: "That's when I'll look around for a pen and bit of paper before the first gig just to write down the running order, who's doing what game, and I'll tell people 10 minutes beforehand.
"We'll have a verbal warm-up backstage then come on and just start doing it. It goes from there, it lasts an hour and that's it, it's done.
"I'm not worried about it or thinking about it because, at this point, there is no show.
"If I had props or I was working out a routine with a juggler and I wasn't sure if he was going to be sober, I could worry about the details but they don't exist because there is no show.
"I've spoken to people about it who have said that's the very thing which would make them nervous, but that's how it's always been."
The 53-year-old performer, widely recognised as a comic genius thanks to his sharp humour and finelyhoned sense of the surreal, is well used to making it up as he goes along.
He works hard at it. He has been doing so every Sunday for 25 years as part of London's Comedy Store Players and beyond with his festival group Paul Merton's Impro Chums, who this time out include Mike McShane, Richard Vranch, Lee Simpson and his wife, Suki Webster.
Paul said: "I'm being nonchalant about it but after 25 years, every week, you sort of realise there isn't anything to worry about.
"Not to suggest I am being complacent about it at all. The show doesn't just happen. You have to make sure your focus is right, you're bringing your experience to bear and if, 15-20 seconds in, something is not working, then do something else or get off, quick.
"We are very conscientious about it. We know if for some terrible reason one night the show didn't work - and luckily we've never had one of those - we can't turn round and make the excuse it's improvised, it's not my fault. It's got to be fun, it's got to be entertaining and it's got to work.
"So you think about the show then, you think about nothing else, but when it's over and done with, you forget about it until the next time because that's that show and it will never happen again."
Two weeks of fresh, original material by one of the masters of modern comedy is one of the Fringe's big sells but there is no pressing reason for Merton to do it. Held in the highest regard by his comedy peers and the public alike, he's a TV favourite as team captain on Have I Got News For You as well as fronting shows such as Room 101 and a variety of documentaries and travelogues. He's here because he wants to be.
He said: "It's the sheer fun of doing the show. It used to be the case that people didn't come back once they were well known on the telly unless they were playing the Playhouse, some sort of lucrative bank job gig.
"I always felt coming back once you were successful and not having to worry about handing out leaflets or putting up posters down Lothian Road at midnight, just enjoying the festival, being part of it without any of the worries about losing money, was something I wanted to do."
It's also, perhaps, something of a reflex reaction.
He has been heading to the capital since the early 1980s gradually working his way to the top year by year, although not without his setbacks.
In 1987, following a triumphant first-night Festival show, he broke his leg playing football and ended up in hospital with a pulmonary embolism which then sent him into a coma. No laughing matter. Perhaps, as a result, he has little sense of nostalgia looking back at his days as a struggling comic, although his humour remains intact.
He bursts out laughing as he struggles to recall fond memories of his fledgling days.
He said: "I can remember getting from the small room I'd rented to get to the venue and it's pouring down with rain. There's no question of getting a cab because you have no money, you can't understand the bus system, so you walk and you arrive at the gig soaking wet and there's only eight people there but you must act pleased to see them because it's not their fault - and these are eight people who have actually paid to come to see you. So, no, I don't miss those days.
"I still feel connected to it all. I've been playing The Pleasance for a long time now and I love the courtyard there. I will happily sit around after the show with the guys who have done the show and have a few beers. I don't feel I'm missing out on the Festival experience - I'm pleased I am where I am.
"The thing is, I look around the Pleasance courtyard and every year there is a whole bunch of new posters by people I've never heard of and every year there are more and more of them. It's very competitive out there."
Paul makes it sound as if he would wilt facing so many rivals, which is perhaps the biggest laugh of all. Alongside Ian Hislop, he's been wiping the floor with politicians and pundits alike on the BBC's comedy crown jewel, Have I Got News For You, for almost 20 years. He takes living on his wits in his stride and in many ways, the show is the perfect preparation for Edinburgh.
He said: "It's a bit like improvisation in that you have to be conscientious about it and do the best you can while you are there. Ian brings such a great energy to it, so any laughs I can get I'm always grateful for.
"Some of the people that come in are very competitive, not just in points but in air time too, talking over you when it's meant to be your turn. That gets a bit irritating at times but they always run out of stamina and in the end you just clear up.
"I win quite often, which is great, but I don't really care about winning, I care about it being a good show. If I get three really big laughs, if you could guarantee that, I wouldn't care if I won another programme."
He's close to his fellow team captain, Private Eye editor Hislop, despite not always seeing eye to eye.
He said: "I like him enormously but he has his blind spots. He hated it when Bruce Forsyth was on, recently, hated it, but there we are."
The ultimate arbiter, as far as Merton is concerned, is the audience. Comedy lives or dies by their reaction, so he makes sure he listens.
He said: "If I wasn't in Edinburgh, I would be at the Comedy Store. You have to keep that connection with the audience alive. It's essential. You need to respect audiences, rather than understand them, and give them your big stuff."
He's not failed in 25 years and, 20 minutes preparation or not, he is not going to start now. You'd be quackers to think otherwise, as he explains.
He said: "If something is not working, we just change it. That's the kind of guarantor, the feel safe factor.
"If I had written a play and it's going badly, 20 minutes in everyone is saying, 'good God when's this going to be over?' and you're in trouble. With this, I can just say, 'look...a dancing duck.'" Paul Merton's Impro Chums is at the Pleasance Courtyard Grand, from August 13-28. Box office 0131 556 6550 www.pleasance.co.uk.
ON THE NEWS... Paul with Have I Got News For You colleague Ian Hislop TAXI FOR MERTON... The comic presented Paul Merton In India for Channel 5 FEST GIG... In Pleasance Courtyard