JIM Davidson’s reputation goes before him like a reverse shadow, reminding the world what an incredible daftie he has been.

While managing to make the nation laugh and becoming a major success story, his life has also been underlined by a series of misadventures; with women (married four times at a cost of millions), with drink (costing hundreds of thousands in cancelled venues), and with his reactionary mouth (at a cost of his reputation, regarded, sadly, as a dinosaur by younger comics).

Today, however, in the London office of the charity he co-founded, Care After Combat, another side of Cameron James Davidson emerges.

The man who arrived on New Faces in 1976 and took on a West Indian voice is speaking in a voice that’s soft and reflective. And he’ll go on to talk about current issues in a nuanced manner, such as footballer Ched Evans’ rape trial, Sir Cliff Richard’s revenge tale and the fear that haunts Davidson himself. Why the earthy, serious chat with someone who so often reaches for the gag at every opportunity?

Davidson is rewinding on his 62 years on the planet because reflection is the theme of his new autobiographical stage show, 40 Years On. “I’ve come up with a production that lets me tell stories,” he says. “I wanted to talk about my life, about growing up in an ethnic family in South East London.” Davidson, whose father was born in Glasgow’s East End, will reveal (The Entertainer-like) for example, what it’s like to go on and face a crowd. In Act Two he will tell tales of his own life. Talking of biography, Jim, can you reveal the real detail of your comedy epiphany?

“Well, I wasn’t a very good window cleaner,” he recalls of his teenage job, smiling. “I was terrified of heights. And it wasn’t at all like Confessions of A Window Cleaner. I was too scared to even look into a bedroom. I just got up to the glass and waved my rag around.

“Meantime, I’d been telling jokes to mates and I thought I was funny but the honest truth is I think my career had a lot to do with amphetamine sulphate.” Seriously? “Yes,” he continues, grinning. “I was in a pub in Woolwich and the comedian hadn’t turned up. It was suggested I get up there but I was terrified. Then someone said to me ‘Sniff this, sonny!’ And that was it. I did a two-hour set in seven minutes. It was like a microwave act, courtesy of speed. I was frothing at the mouth when I came off.”

As if he’d been bitten. And he had, by the fame bug. Davidson picked up £6 for his Sunday lunchtime comedy spots, gave up the dirty windows and changed his name to Jim. “So I didn’t have to pay tax on it,” he says. “But I’ve made up for that since.”

He has, becoming a national celebrity in the Seventies, fronting a sitcom, storming TV variety shows, presenting the Generation Game. He had a Rolls-Royce once. “I remember parking it outside the London Palladium, with a speed boat attached, waiting for me when I finished a Royal Variety Show to drive off to Torquay. And off I went with Miss Great Britain, Carolyn Seward, on my arm.”

Happy days, indeed. Well, some of them. Along the way, headlines appeared about wife-fights, bankruptcy, removing himself to Dubai. In 2013, Jim Davidson was arrested over a series of historic sex abuse accusations. No charges came from it but Operation Yewtree cost him more than £100,000 in legal bills.

“What became slightly upsetting for me, and I think for the police as well, the bobby on the beat, is that the complainant is assumed to be the victim,” he says in calm voice. “In fact, the policewoman who arrested me told me she was told to treat the accusations as the absolute truth, until they can find proof that isn’t the case.”

Davidson reveals, astonishingly, a sympathy with the police. “I think the Jimmy Savile situation forced the police and the Government to act, because they were so afraid of another public inquiry. The result was Operation Yewtree, and the feeling ‘Well, we’ve got a couple (of sex abusers), that will do.’ And people like me were used as human fly paper. It’s unfair on celebrities, but what do you do? It doesn’t work if it’s Fred Smith around the corner. It only works when it’s someone in the public eye. Then thousands (of complainants) come out of the woodwork.”

We go on to talk about the recent case of footballer Evans and his second rape trial which this time saw him cleared. Davidson argues both sides of the fly paper should be used. “I feel sorry this young lady was dragged through the dirt and her sex life revealed. But it has to be about a search for the truth. What the defence did was look for a pattern, as the prosecution had done with me. But, and here’s the ‘but’, her name hasn’t been dragged through the courts, because we don’t know it.”

The comedian pauses. “And while Ched Evans has been found innocent – and I’m certainly not saying he’s a nice man – as soon as he plays at a football ground like mine (he’s a Charlton Athletic fan) his name will be chanted – and not in a good way.”

Davidson reveals he’s been in talks with radio presenter Paul Gambaccini and Sir Cliff, who are campaigning for anonymity for those accused of historical sex crimes.

“I can understand their anger. But when it comes to suing the BBC and the police I’d say ‘Let it go.’ What happened to me was dreadful. I knew people were thinking ‘No smoke without fire’ and 98 per cent of young comics hated me and my first question to my lawyer was ‘Who do I sue?’ But he told me to write a book instead.”

And now a play, in which Davidson may even talk about his great fear, which he now reveals. Of not being Jim Davidson any more. The insight emerges as we talk about the loss of his great friend Keith Emerson, the keyboard leader of prog rock band Emerson, Lake and Palmer, who took his own life earlier this year.

“On the day Keith shot himself in the head he had had the result of an MRI scan, taken because he had lost his ability to use his fingers. But what he had also lost, in his mind, was his relevance. He was a big, big star, not in the current pop world or with anyone who has ever worn Ugg boots, but in the rock world. I call it the Alvin Stardust problem. What happens when an Alvin has no money and he has to take a bus? And he has to put up with the selfies. Michael Barrymore suffers this to an extent and, in a way, me too. Thankfully, I can still go on tour.” His voice softens, and he reveals an introspection Britain doesn’t usually attach to the man. “I’m still Jim, but there are two things to bear in mind about carrying on. You have to be able to deliver and enjoy the performance. And the audience have to come and see you. They never leave you overnight, but they do leave you one row at a time.”

Davidson also needs to tour for financial reasons. “I want to put on a show for Keith at the Royal Albert Hall and a bank manager told me they’d back me, if I gave them a personal guarantee. He asked about my assets and I told him ‘Carp fishing gear.’ He said ‘Don’t you have a house?’ and I said No. the current wife owns it.” (In Hampshire).

Davidson can’t resist making a gag. “I’ve never sold a house in my life. They all just seem to go.”

Does he regret the past that’s created the present, the fights with the ex-wife that produced black eyes, the non-PC alienating comments, the squandering, mad man moments fuelled by drink (he still loves Glendronach, at £150 a bottle)? Should he have led a more sedate life?

The comedian offers a wide grin. “Sometimes I regret some of the things I’ve done, but then I remember an Andy Capp cartoon with him saying to Florrie, ‘I’ve just read that alcohol is bad for you, so I’m giving it up.’ She says ‘You’re giving up drinking?’ And he says ‘No, reading the papers.’”

Forty Years On, The Clyde Auditorium, November 24, and the Alhambra Theatre Dunfermline, November 25.