As Tom Green’s new play reveals the darker side of a British comedy legend, star Damian Williams admits he built his reading of Tommy Cooper around one single YouTube clip.

“No one ever saw Tommy not being Tommy,” says Williams, as he walks down London’s Oxford Street.

“There is no footage of him being himself and talking about his life as a performer.

“There’s just this one bit on YouTube where they catch him offguard.

“Someone is talking to him about his career, saying, ‘It must be quite exhausting.’ Tommy just looks down and says, ‘Yes, it is.’ And he means it.

“It’s him without the clown’s face on. I took it all from there, that one line.”

Being Tommy Cooper, which premiered last year as a one-act play at The Old Red Lion in Islington, is based around a disastrous series of Las Vegas shows in 1954, when Tommy and British Forces’ sweetheart Dame Vera Lynn were on tour together.

“No one knew who Vera Lynn was,” says Williams, who toured the country in farces and comedies with Bruce James Productions until it ceased trading in 2012, as well as hosting Sky One’s Are You Smarter Than Your Ten Year Old?

“Tommy came home because his act was bombing, which was around the time that his television career was starting.”

With news of the national tour in 2013, Green extended the play into a two-act piece, adding extra scenes.

As well as looking unflinchingly at Cooper’s excessive drinking, it also looks at his rocky “hate-hate” relationship with his agent Miff Ferrie and the beginnings of his 17-year affair with his assistant Mary Kay.

Looking on is former vaudeville act Billy Glasson, who is trying to sell Cooper some new jokes.

Secret affair

“Some people know he liked a drink but I don’t think people realised he had an affair with his assistant,” says Williams, who admits he has been a Cooper fan for many years.

“The pressure he was under all the time – he was the comic’s comic, comedians regarded him as the best – I think that’s why he drank so much, to take the edge off it all.

“It couldn’t happen today with Heat magazine trying to find out the gory gossip for every celebrity. In those days you didn’t know anything about them – they had people around them keeping it quiet.”

To play Cooper, Williams had to learn some of his classic tricks.

“People don’t always get that to do something wrong you have to know the trick backwards,” says Williams. “It’s like Les Dawson playing the piano – to play the bum notes you have to know the tune in the first place.

“It’s interesting to learn all the little bits of magic – it ruins a lot of the tricks. You come away thinking, ‘That’s it? I always thought it was more complicated!’ “A lot of the time if you had sat down for five minutes it would have been quite obvious how the trick worked. I’ve learned a lot doing it.”

He has also mastered how to play a convincing drunk – to the point a stage manager at Islington thought he’d had a few before taking to the stage.

“A true drunk is a man who thinks he’s not drunk,” says Williams. “I remember Michael Caine doing a workshop on it when he did Educating Rita. That stuck in my head – the art of the drunk is to fool the world into thinking you’re sober.

“When I heard about the stage manager I thought I must have pulled it off!”

Despite it being nearly 30 years since Cooper’s sudden death onstage during a live television broadcast from Her Majesty’s Theatre, the legend lives on.

“He’s still a cult figure,” says Williams, who has received well-earned comparisons to Cooper himself when playing comic roles onstage.

“You can’t mention his name without someone doing an impression of him – it’s like a form of Tourette’s. There are young people watching him on YouTube, while a lot of other comics from the same time such as Stanley Baxter, Larry Grayson and Dick Emery aren’t known.

“There are no new versions of these stars because no one had to work as hard as they did. No one tours the country doing clubs every night to build up their act.

“He never stopped working – even when he was ill they were pushing him on to television programmes. You can see he’s quite slow and pottering about because they’d just shoved him on.

“I have never done one-nighters before – I’ve always done weeks away. It is exhausting.

“I’ve got to the stage where I wake up and think, ‘Where am I?’ He would have done the same.”