Funnyman Paul Merton reveals how humour has helped him through both good times and bad.

He may seem somewhat dour and straight-faced when satirising politicians and celebrities on the long-running panel show Have I Got News For You but Paul Merton is surprisingly cheerful in conversation.

His deadpan and at times surreal comedy has endeared him to millions over the years and has been his own therapy in times of trouble, he admits.

Now appearing in the 58th series of the TV news panel show, Merton, 62, has also found time to bring out his new book Funny Ha Ha, a collection of 80 funny stories by the great and the good, from Anton Chekhov and PG Wodehouse to Nora Ephron and Victoria Wood.

It's a huge anthology, a hefty weight, he agrees, but one which is easy to dip in and out of, not to be read in one sitting.

"I probably read four times the amount of stories that are in there. It took over two years."

The stories span 200 years yet some comedy remains timeless, says Merton.

"There's a view sometimes expressed that comedy dates, but not necessarily. Some does, some doesn't. PG Wodehouse seems to be very much of his time, the 1920s, even when he was writing in the 1970s. But the best of his stuff stands up remarkably well.

"If something's very topical it can lose its appeal, or if it's a parody of a novelist that we no longer know, but generally speaking there's nothing in the book that feels old or past its 'tell-by' date."

The book is dedicated to his third wife, fellow comedian Suki Webster, whom he married in 2009. They have been performing improvisational comedy since the late 1990s, touring as part of Paul Merton's Impro Chums, and became a couple in 2004.

But there's no competition between them, he insists.

"We enjoy doing stuff together - she's in the Impro Chums when we tour and she does occasionally do The Comedy Store Players. There's no rivalry between me and Suki. Impro is all about having fun with your friends."

Touring with his wife has meant that they can share the humour as it happens spontaneously on stage.

"You can't tell someone about what was in the show because it won't seem to be amusing unless you were there. If I was touring or she was touring and the other one was staying at home, that would be more lonely. The fact we do it together is great. We both know what the gig was like and I'm working with somebody I love."

Recently he appeared in Webster's Radio 4 play, My Obsession, the story of a midlife comedian becoming unexpectedly close to his most obsessive fan.

"That was great fun to do because most of the stuff I do is improvised, so to have a script in front of you which you don't have to learn because it's radio is a very enjoyable way of doing comedy."

Laughter has been a key part of his wellbeing through some tough times, he agrees.

"Comedy always is important, though good times and bad times, laughter is a release. And in the general act of laughing, while we are laughing at something that's funny, nothing else in the world exists at that moment. Your brain is full of endorphins. When you are laughing hysterically, you're not thinking about the mortgage, the children's education, the state of the country or how Arsenal are doing."

It has helped Merton through his own crises including a short stay in the Maudsley Psychiatric Hospital, where he checked himself in in 1990.

In his 2014 autobiography Only When I Laugh he describes experiencing a heightened state of excitement, but when he started rambling and crying, telling a concerned friend that he thought he was Jesus, it was time to seek help.

While some speculated he was suffering from depression, Merton has said his manic behaviour was down to anti-malaria tablets he'd been taking for a holiday in Kenya.

Years later his life fell apart again when his second wife, producer, writer and actress Sarah Parkinson, died from breast cancer in 2003. Yet he was back at The Comedy Store the following week.

"To be in a room full of people who are laughing is a good place to be. There's happiness in the air. Standing at the back where nobody can see you rather that just sitting on your own at home, it was a release, definitely," he says now.

"It releases tension and makes you feel better, even if it's only a temporary thing. It was a respite, an escape from harsh reality. It's very good for your mental health."

The shy son of a London train driver, Merton grew up in a council flat in Fulham and later unsuccessfully auditioned for RADA, subsequently ditching his job in an employment office for a comedy career.

He clearly remembers his first comedy gig, in April 1982 at The Comedy Store in London.

"I'd written a monologue based on a police case in Wales in the late Seventies called Operation Julie where the police had raided this factory that was making the drug LSD. There was LSD dust in the air which they sort of ingested and they didn't know what was happening to them.

"I remember seeing an interview with a policeman sitting in a pub talking about his hallucinations in a very dry policeman-like way. The sentence was something along the lines of, 'I was sitting in the pub with Detective Inspector Norris when I noticed that my pint of beer was getting bigger'.

"I saw the possibility of a sketch of a policeman in court relating an hallucinogenic experience but in that dry policeman-like manner. It was about three-and-a-half minutes long and the first time I did it I thought it was funny.

"The audience loved it and there were cries of 'More!' I didn't have any more so I went back on and did it again and walked home in a haze of happiness from Soho to my bedsit in Streatham, which took three or four hours, just blissfully stunned. There were tougher gigs after that, but it kept me going for the next 18 months."

Some 37 years on, he's still appearing at The Comedy Store on Sundays, and is still touring with his Impro Chums show with Webster.

And then of course, he's a regular panellist on BBC Radio 4's Just A Minute and has his weekly HIGNFY appearances.

"I'm glad that the two news stories, Brexit and Trump, have moved on from where they were. They seemed to be stuck for a long time. When I was doing stand-up a long time ago I never had political jokes - I'm not that engaged or interested. It doesn't fuel my comic energy.

"I'm much more interested in stories about weird animals doing things or the man who marries a piece of toast."

Does he see himself branching out into theatrical dramas like fellow comedians Sir Lenny Henry, who has played Othello, and David Mitchell, who'll be starring in the West End as Shakespeare in the adaptation of Ben Elton's TV comedy Upstart Crow next year?

"I did a panto last year at Wimbledon Theatre as Widow Twankey," he offers, deadpan. "That was a new departure and was well received."

Funny Ha Ha: 80 Of The Funniest Stories Ever Written, selected and introduced by Paul Merton, is published by Head Of Zeus, priced £25. Available now.