Les Dennis tells this story about the moments before curtain up on his one-man play in Edinburgh. In front of a curious crowd that was rapidly turning into a who's who of British comedy, Dennis was about to play the role of Jigsy in a production inspired by the late and (nearly) great Liverpool comic Jackie Hamilton...

"I was peeking through the curtains to see who was coming in. I saw Steve Coogan, and then Jimmy Carr and I thought 'oh shit' but actually it was all OK and Jimmy was one of those who came up afterwards and said it was great."

Phew.

Jigsy earned critical approval at the Edinburgh Festival Fringe in August but an even greater challenge lies in wait when Dennis reprises the role in his home city of Liverpool later this month.

Initially known for his comedy impressions and TV work alongside Russ Abbot and Dustin Gee, the 59-year-old consolidated his career with a 15-year stint as the host on ITV's game show Family Fortunes.

But for many years now Dennis has quietly gone about building an impressive CV as an actor in television, theatre and musical theatre. "People look at my CV and say 'I didn't realise you had done so much'. It was a case of changing people's perceptions and being taken seriously by casting directors."

A quick check of his biography shows the roles have come thick and fast - Me and My Girl and Chicago in the West End, Ayckbourn, Priestley, a UK tour of Art plus numerous TV parts in shows such as The Bill and Holby City.

One of a growing list of comedians who have successfully made the switch into 'serious' stuff - think Lenny Henry, Jimmy Jewel and Mike Reid to name but a few - Dennis arrives for our 10:30am interview bang on time and feeling knackered. It's his first day off in ages, and he's wondering what to do on a rainy day in Leicester and reckons he may head for the cinema later on ("the new Brad Pitt").

Dennis is in Leicester finishing his role as McBride in the hugely popular Certified at the city's Curve theatre. For a while he was rehearsing Certified by day, playing Jigsy in Bristol at night and had just left a UK tour of Legally Blonde.

A four-man show about what it is to be male in the 21st century, Certified is both moving and blisteringly funny - as well as useful practice for Dennis when he returns to his role as Jigsy (pictured below), a washed-up comic in a working men's club.

So what is it about funny men and this shift into acting? "It was always in the back of my mind to do it," he says, citing the influence that his visits to the Liverpool Everyman theatre had on him as a teenager. "In those days you could watch great acting from people like Jonathan Pryce, Bernard Hill, Alison Steadman and Bill Nighy.

"I just loved watching these brilliant actors. I used to buy Plays and Players magazine and see the adverts for drama schools and think, 'Should I be going to drama school as well?' But by then I was already doing the clubs."

Dennis had fallen in love with variety even before this and, by the time he was 17, was a regular on the club circuit. He even recalls a couple of gigs on the same bill as Jackie Hamilton himself. "I was fresh-faced and looked about 14. I was going on in between these men and just about surviving. I had a bit of help. My mum was my chaperone because I didn't drive," he says.

"She had a good singing voice and, if I was having a hard time, she would get up and do a couple of numbers. At first the punters would say 'oh, he's so young, bless him', but then if you were getting paid semi-pro wages they wouldn't take any prisoners.

"They were great days," he remembers. "Great experiences. And bad ones too, like concert secretaries docking your money or the curtains closing on you."

This immersion in comedy, a fast-track education for the young Les Dennis, proved invaluable as he learned that making an audience laugh was not just about the timing, but representing truth as well. "Audiences know when you don't mean it." And this helps the good comics to make that leap, he adds. "The masks of comedy and tragedy are the flip side of one another. It's not that the funny man wants to play Hamlet - more precisely, anything funny is on the edge of being tragic."

Acting coach Geoffrey Colman has noticed that more comedians want to "embrace the world of character". Colman, head of acting at Central School of Speech and Drama, worked with Lenny Henry prior to rebranding himself as a serious actor. The Daily Telegraph called his Othello an 'astonishing debut'.

The comedian is well-placed to be an actor too, adds Colman: "The comedian's inner world - a world that feeds his or her stories - is the same world as that of an actor. The technical mastery of that world - its body design, its vocal note is embodied in the same way. But the crucial difference is that the comedian is more often inhabiting this world as a direct address to audience, whereas the actor inhabits a world observed.

"The comedian in transition must therefore take on this slight adjustment and be content to be denied the fizz of eye contact and banter. Not all comedians are able to come off this fix."

So while the intent for Dennis to have a serious go at acting had always been there, the opportunity presented itself through hosting Family Fortunes. "It took me three weeks a year to film it and that enabled me to fund my acting and to go off and do rep and then Me and My Girl in the West End."

Understanding the darker side of comedy, Dennis explains, was one of the factors that drew him to the character of Jigsy. Using Jackie Hamilton as a template for Tony Staveacre's one-man play, Jigsy is a jobbing Liverpool comic at the fag end of his career, spinning stories about the old days and fearing the punters are more bothered about the bingo.

"When Tony came to me with the script I was really intrigued that, as a Londoner, he had captured the sense and language of a man in a dressing room in a Liverpool working men's club. For 75 minutes this character can sit here and talk about his comic heroes, and talk about the career that he nearly had. It's very moving at times. This is a guy drinking himself to death. He's a nearly man, and it's the death of a showman."

Hamilton died in 2003 but Staveacre asked for permission from the funnyman's family to write the play. Dennis adds that the comedian's sister and nieces were in the audience during the Bristol run of Jigsy in September. Dennis admits they were not sure how Jigsy would be received in south-west England, yet "on word of mouth it sold out".

Taking it home to Liverpool, however, is a big deal for a local lad who started in the clubs. "I'm really nervous on the one hand but also very excited."

There is cautious optimism that Jigsy will play elsewhere once the Liverpool run is over, but first on the diary for Dennis is his debut as a panto dame in Aladdin at Crawley followed by filming an Easter special of Life's Too Short with Ricky Gervais and Stephen Merchant.

"It features Keith Chegwin, Shaun Williamson and me," Dennis says, with a playful smile on his face. "We're playing twisted, demented versions of ourselves. Ricky calls us the Twat Pack."

And after that? "Like any actor, you are just waiting to see what's next." Perhaps he'll peep through the curtain again, but one suspects he doesn't need to anymore.

Jigsy is at the Royal Court Theatre, Liverpool, from 23rd October to 3rd November 2012.
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