Comedian Raymond Mearns on his father's deathbed admission

But if the likes of Ken Loach – who featured Mearns in two films – are in agreement about the comedian’s immeasurable talent, will be confounded in equal measure as to why the funny man isn’t on the A list.

Mearns, after 25 years in the business, has long looked to be captured by major success, yet somehow has avoided its preying searchlight, lurking instead in the dark basements of dank comedy clubs, in out-of-town theatre venues or the cabaret rooms of swish-draped hotels where he performs the odd after-dinner.

Over the years, Mearns, described by Billy Connolly as “a man who knows how to swear properly”, has offered his own reasons for not hitting dizzier heights. Alcohol is certainly up there alongside Arrogance. And Conceit.

“When I was 25 and p***ng vinegar I figured I was Billy Big Baws and began to believe I was special,” he says, over a nice chilli soup in a Glasgow West End restaurant. “You don’t want to listen when someone tells you ‘You’re a fat bawbag.”

Indeed. But the passing years haven’t really tempered Mearns’ natural instinct for shoving his fingers in his ears whenever someone in authority seeks to offer direction. The comedian recalls a fairly recent meeting with a BBC controller who had called him in to talk about work.

Instead of shutting up and listening, Mearns went on to tell the comedy boss where he’d gone wrong with his output in the last five years. He shakes his head in almost disbelief at his own donkey-level stupidity.

“I also f***** up a film audition for Sunshine on Leith,” he recalls. “Dexter Fletcher was the director and my audition called for me walk into a room and to sing 500 Miles. But no, not me. I’m a guitar player and I decided I really wanted a shot of the guitar that was being played. People looked at me as if to say; ‘What the f*** are you doing?’ And they were right. I was nuts.

“But I would do mad stuff before going up for corporate work as well. I remember I went up for a Bank of Scotland commercial and told the bloke off for not employing me more often.” He takes a sip of his soup and adds: “I’ve been self-sabotaging for years. That’s the truth.”

That’s undeniable. What’s intriguing is trying to work out why? Tell me about school years, growing up in Glasgow’s East End? “Eh? I didn’t realise this was going to be a therapy session,” he says, smiling. “I just wanted to get some punters in for this new tour.”

Humour me, Raymond. “This isn’t stuff I usually talk about. Well, I went to eight different primary schools,” he offers, and lists their homes, across the East End, including one in a caravan park. Why? “Well, my da’ was a cruel, violent alcoholic who would never pay the rent so we’d flit all the time. He kept leaving my mother (he grew up alongside three brothers and a sister) and she kept on taking him back.”

I’m guessing you and Dad weren’t connected at the hip, Raymond, that you couldn’t reveal your secret dream of becoming a guitar player in a band (Mearns has a huge collection of guitars and proclaims himself talented) or about the dream of being a performer? “Naw, never,” he cuts in hard. “He would have said; ‘Your heid’s full of broken bottles, ya ****’. I hated the man.”

The flitting stopped and life at St Andrew’s Secondary school began promisingly. “I was bright but gave up on school half way through fourth year. By this point I was being bullied, harassed.” The easy smile on his face dissolves into something far more sinister. “I almost had this Nietzschean ideal of donning a ski mask and getting a baseball bat and attacking these people,” he admits. “But then I read this book, which taught me to ignore the bullies. And it worked.”

But the damage had been done. Mearns had grown up with the sense of being useless, an outsider, chubby. He came up with the idea of escaping to the army to get out of Glasgow but a congenital hole in the heart condition killed off that idea. He landed a job with a local ironmongers, “before I was binned, when they found out I was a Catholic,” he recalls. “Well, to be honest, I can’t prove it was sectarianism. And at the same time, I had a big mouth. I could have kept my head below the parapet.”

The 17-year-old landed a sales job in Hertfordshire, and lasted three weeks. “I got bloatered every night on the drink and dope and I was sacked for being a nutjob,” he says. He came home, then went back south, this time selling fire extinguishers. “I was quite good at it, despite having a Glaswegian accent almost impossible to understand. But one day after I’d had a blank day, my boss, who was from Paisley, slammed me against a hotel room wardrobe. There was that much pressure to succeed. So I told them to ram the job.”

At 18, back in Tollcross, he fell in love and married Sharon. “Suddenly I had two kids. I didn’t realise it at the time, but that wasn’t where I wanted to be. I was playing at houses when I really wanted to be playing guitar in a band.” Or telling gags. But he couldn’t admit that to himself. Meantime, he had to progress to feed his family. “I’d landed a community work programme having lied about having seven o grades, which got me day release at the College of Commerce. When it was over I asked the tutors if I could keep on coming in and thankfully they let me.”

Five years later he had a degree in business. “I took a degree so I’d never have to work in sales again.” But it didn’t work out that way. Mearns worked his way up the corporate ladder and into a top job with BP. But aged 26, the hole in the heart issue resurfaced and the illness denied him full-time work, and he had to go back into sales. He moved to radio station Scot FM, where he was sacked for having no driving licence.) “I then worked with the Glasgow Psychic Centre. Sacked again. But I did see it coming.”

Seems the sackings weren’t all his fault but he admits he was still drinking to the point of “insanity.” Wasn’t he afraid he was following perfectly in his father’s footsteps? “I never rationalised it that way. You don’t. You just carry on.”

Meantime, Mearns’ guitar playing at parties had evolved into something more. He’d find himself performing skits and gradually added his own material. His wife reckoned he was funny enough to make money out of the laughter business.

“I remember doing a gig a Blackfriars in Glasgow and I came up with this five-minute routine about Wallace Mercer [the late Hearts chairman] trying to pump Tessa Sanderson. I had no idea what I was doing but it seemed to work. Then I was offered another gig, in Greenock." He shudders in recall: “I was offered a half an hour spot but I only had a five minute act. I died that night.”

But the comedy dream had seduced him. “Comedy is about money, fame, power, women, drugs,” he says of the reasons for entering the business. “You feel powerless in your own life so you go into comedy. Nobody will listen to me in their living room but up on a stage that’s different.”

Mearns continued to work, “all the toilets of the west of Scotland.” He regularly appeared at a rundown hotel in Largs. “The place had two toilets. One had a seat and the other had a lock. You could have comfort – or privacy – but you couldn’t have both.” It was while working at Flanagan’s that Kahleen Crawford, now a top casting agent, recommended him to Ken Loach for a role in Ae Fond Kiss. Other film offers followed but he didn’t really build on film and TV appearances. And in 1997 he blew the chance of national fame when he landed the Big Big Talent Show with Jonathan Ross. “I died on my hole,” he says, succinctly. “I let the nation down. I had no idea what I was doing, even though I’d been doing it three years.” He’d thought he could wing it. Conceit. Arrogance.

He says that from 2003-2011 he landed “loads" of work but in 2012 he finally split from Sharon. It was a traumatic period. “I went a bit mad at the time.”

Mad with the drink. The demons had returned. Which brings us back to the theme of self-destruction. Did he seek professional help? “Oh, aye,” he says, and talks of theories such as confirmation bias. “You hear a theory such as ‘talent always doubts itself’ and you think ‘I‘ll take that. It’s easy to grasp onto to’.”

It all suggests you’re afraid of success, Raymond, or feel you’re undeserving of it. Maybe that’s why you don’t graft at your comedy routines like Bridges and Boyle do. Maybe that’s why you tell BBC commissioners who can give you lots of work they’re clowns?

“I thought this interview was going to be easy,” he says, with a wry smile, then adds; “You’ve never really liked me, have you?”

What? Where do you get that from? “You wrote a review about me a few years ago, at the [Edinburgh] festival, and you described me as ‘potty-mouthed’.” What? Not me. I’d never use such a fatuous cliche. I’d have trashed you far better than that. “No, you did.” He Googles the reference, then comes back with an apology. Turns out it was another Herald reviewer. He’d gotten by-lines mixed up.

But this is another example of the paranoia, Raymond? Maybe the world isn’t out to hate you at all. (He’s just landed a new Channel Four film, Limbo, set in Benbecula) “OK, you’re on the right lines here,” he says. “The truth is I’ve never had the balls or the bravery to go any further. I’m an a*******.” He adds: “I’m a confident fool. I think I’m smart but I’m a moron. And I wonder if I lack the real guts or the belief. Anne [his second wife] says audiences don’t realise that what I’m saying up there about my life is actually true. They don’t know my life is a lunatic asylum.”

Mearns was a window cleaner (“cash in hand”) when he married first time round. And what’s clear as a window cleaner’s first window of the day is his early life has been a confidence wrecker. But did he ever manage a peace, of sorts, with his dad?

“When I was on the comedy circuit one year I met this guy who’d just buried his dad and he was grieving. But I said to him, ‘Listen, I’d love to bury my dad. I hate the f*****. .’ But when this bloke told me his story about him and his dad, real Hollywood stuff, it drove me into such a depression. It took me a couple of months to process all this. And I reckoned I had to learn to forgive him so I’d take the kids to visit him.

“Then when he was dying, his liver gone, all yellow skin, the lot. I was at his bedside. And for the first time in my life I stayed silent. I just listened to him. And it turned out he had been a singer and guitarist in a band back in the Sixties. I was amazed. It was sad. I realised this was a real waste of talent.”

So what does that story tell you, Raymond? “It tells me this interview hasn’t gone the way I’d expected,” he says, grinning.

Raymond Mearns: Confessions of a Control Freak tour opens March 29, as part of the Glasgow International Comedy Festival, at the Stand Comedy Club in Glasgow with dates throughout Scotland. Check out www. Raymondmearns.com.