"It was a crazy, happy, carefree time and I shall never, ever forget it as long as I live."

Paul Merton is reminiscing about his salad days, that euphoric period many, many years ago when, as he revealed during the last series of Have I Got News For You, he enjoyed a brief but intense affair with the former Bishop of Galway, Eamon Casey.

"Doctor Eamon, that was my petname for him, Doctor, was a wonderfully sexually-attractive individual," he recalls. "You just had to look at him. He was a fine figure of a man. I found him impossible to resist.

"It broke my heart when all that stuff about his son came out. And that other woman. He never told me about any other woman. I thought it was just the two of us, me and Eamon."

The above trip down lovers' lane is characteristically delivered by Paul Merton in that gold-plated deadpan for which he has become a byword. Dubbed "TV's Mr Glum" and described by his HIGNFY adversary, Ian Hislop, as "a dangerous alien from the planet Stroppy", Merton's sullen, pouty visage has become the proverbial face that launched a thousand quips. It may be an integral part of his act that he never even cracks a smile while he's performing but it's a safe bet that, these days, he is to be regularly found chuckling all the way to his local financial institution.

At thirty-six, Merton is undoubtedly the biggest, and busiest, star in British comedy. In 1992, he scooped the U.K. Comedy Award for top television personality and more recently he became ITV Comedy Personality of the Year. Along the way, he has tied up a deal with Channel 4 for further series of his sketch show, secured a publishing contract for Paul Merton's History Of The World (which should be in the shops by Christmas) and undertaken a major fifty date tour which this week brings him to Dublin's Olympia for five nights. In between all this, there was a regular column for the Sunday People which he recently decided to cease due to the pressures of other commitments, another column for Family Circle magazine, and his Imperial Leather soap ads for which, he says, he made a sum of money that was so large he finds it embarrassing to specify. Now, there's even talk of a film project.

For Merton himself, however, the real pleasure of success is not so much the fame or the cash as the fact that he is now taken seriously as a force in the comedy world and that he is given the opportunity to do a variety of different things.

"In the field of television comedy particularly, very few people seem to know what they're actually doing," he says. "So, anybody who's got any kind of instinct about it immediately gets snowed under with offers to do this thing and that thing. I've been offered all kinds of things and, initially, I took everything cause I didn't know how long this was going to last. But now, I'm saying no to most things. I want next year to be less hectic than this one. I've got to find an easier pace for myself."

Ironically, for someone who is renowned for lavishing intense and concentrated effort on the crafting of comedy, it's as an ad-libber that Paul Merton is best known and admired. His sketch series (ingeniously entitled Paul Merton - The Series) is the product of six months solid graft, during which ideas are constantly refined and polished with his co-writer, John Irwin. Merton's perfectionism is legendary: props are specified to the last centimetre, precise shades of colour for backdrops are delineated in his scripts. Yet despite such scrupulous attention to detail, his sketches are often hit-and-miss affairs. By contrast, his spontaneous contributions, and indeed interruptions, on Have I Got News For You are almost always hilarious enough to have both viewers and fellow contestants weeping with laughter.

Throughout the five series of HIGNFY, Merton has become increasingly proud of his top-of-the-head wisecracks and his ability to throw the kind of curves that so regularly transform the news quizshow into something far more surreal and gut-wrenchingly funny than mere satire. At some point during the recording of almost every single show, he has mentioned the fact that whereas host Angus Deayton's comments are scripted, his are not. On Deayton's insistence, however, these remarks are always edited out.

"Of the forty-eight shows that we've done, I've probably said that about forty six times, knowing full well that they'll never use it," he states. "Angus does not want to spoil the artifice of it, that's what he says. He doesn't want people to know that he's reading off autocue so I just mention it at every opportunity really."

Apart from these attempts to undermine Deayton's artifice, however, Merton insists that very little is recorded that doesn't make it into the finished programme. "We don't waste much time doin' stuff which we know is libellous and we know is never going to be used," he says. "It might get an absolutely huge laugh but if it's not going to get in it's just a waste of energy. We record about forty minutes on the Thursday night before it goes out and you see about thirty so there isn't much wastage."

Of all the politicians and celebrities who have guested on HIGNFY, who does Merton reckon was the worst and least funny?

"There's been a few who've been pretty useless, really," he replies. "But the worst was that Tory MP, Jerry Hayes. He talked non-stop for the entire show and nothing that he said was any good at all. So, when it came out the next day he was very heavily edited and he was rather upset about this. He phoned up and complained. He had no idea that what he was saying wasn't funny at all. Some MPs get carried away with this idea that the House of Commons is a hotbed of witticisms. But what passes for a witticism in the House of Commons is pretty weak if you put it under the sharp focus of daylight."

Merton claims to be completely unaware of the attempts to launch an Irish version of HIGNFY and of the debacle which eventually surrounded the scrapping by RTE of Dermot Morgan's Newshounds before it even got off the starting blocks. The story does not surprise him, however.

"Have I Got News got off the ground primarily because there was no publicity about it whatsoever beforehand," he asserts. "It just sneaked out on BBC2 one night and gradually built up an audience. It wasn't until about the third series that people started calling it the funniest show on TV and so on. But, I think, if we had made a big song and dance from the start about how much we were goin' to slag people off and how so-called subversive we were gonna be, we wouldn't have had a chance of getting off the ground. We took them by surprise."

Of HIGNFY, Merton has said that "Ian Hislop is the conscience, Angus Deayton is the brain and I'm the spleen" - is he suggesting that behind the glib exterior there lurks an angry young man?

"Not really," he avers. "I was just trying to make a joke and I picked the wrong word. Spleen makes it sound like I'm angry. I should've said 'I'm the pancreas'."

Was he ever an angry young man?

"Yes, about five, six years ago," he says. "But then I was just angry about selfish things like my career and why I wasn't more successful and why was that person on telly and I wasn't. Petty jealousies really, you could say, but I was very angry about what I perceived was a situation where I was kinda being left behind in career terms."

Much has been said in recent months about Merton's alleged "nervous breakdown" in 1989. Almost all of it exaggerated, he insists. "I never had a nervous breakdown," he explains. "I had a manic episode. It was from over-work, really. I was writing my own first series at the time and writing Sticky Moments with Julian Clary in the afternoons and doing Whose Line Is It Anyway in the evenings. It was manic, I was manic and eventually I saw a psychiatrist guy and he said that if I'd gone on for another year I would've had a nervous breakdown.

"It was the opposite of manic depression in that I was having the time of my life. Everything was wonderful and great but I wouldn't stop. I was working on adrenaline rather than real energy. But, at the time, I was sorta being constantly creative and not just in terms of my work. I'd walk into a pub or something and I'd think 'This pub would be so much better if the bar was over there and if they had this or that'. I had ideas for everything, sort of mental hyper-ventilation."

Paul Merton is obviously very happy with his current fame and role as everybody's favourite funnyman. However, he is also acutely aware of the dangers of over-exposure and extremely wary of the kind of hype that can surround some comedians, not least himself.

"You read all this stuff about 'comedy being the new rock'n'roll' but it's daft really," he says. "It's like saying 'Lemonade is the new foam-rubber'. When I see comedians on the cover of NME, I wonder if the same fate will befall them as so regularly befalls rock bands. The build-em-up-knock-em-down syndrome, the faddishness that goes with rock bands, the fact that so many people grow out of those things that they loved so much as teenagers. I don't think comedy will ever take over from rock'n'roll. You'll never have spotty-faced teenagers standing in front of a mirror going 'A funny thing happened on the way to the pub'.

"The thing about me and all the magazine covers is that I only agreed to do that stuff to publicise my Channel 4 show. If I'm not publicising something like that, I'm not really interested in doing interviews. The nice things that people say about me now don't really affect me so if there's a backlash I don't think I'll be too bothered by the nasty things. It's the inevitable swing of the pendulum."

So far, reaction to Paul Merton's British tour has been extremely positive. It is, he says, a mixture of stand-up, sketches and improvisation and, with the exception of about ten minutes of material from Paul Merton - The Series, is all entirely new. No stranger to Ireland, he is particularly looking forward to his Dublin shows.

"My mother is Irish," he says. "She's originally from Waterford and she and my father have now retired to Cork. I know Cork very well 'cause I have cousins there and I spent five or six summer holidays there. Dublin, I don't know so well. The last time I was in Dublin I was about sixteen. There's loads of pictures of me standing beside bridges and things, for some reason. My cousin, Peter, got married in Ireland last year and I had a great time at that so I'm really looking forward to actually working there for the first time.

"Who knows? Maybe even Eamon and I might meet up again. They do say that true love never dies, don't they?"