WHAT a life Ray Cooney has, you suggest, when his first thought upon waking is how to contrive a young lady into her underwear, or create a scenario whereupon a middle-aged buffoon finds his trousers draped ignominiously around his ankles.

“It’s not quite like that,” says Cooney, smiling. “The process of writing farce is rather different.”

Cooney should know. In his career, the actor-turned-writer has created 17 West End hits. Now that Brian Rix is gone, Cooney is the undisputed godfather of farce, a man who understands implicitly the world of door-slamming, window-jamming, underwear-revealing chaos.

Farce, of course, has existed since couples began taking their clothes off in places and with people they shouldn’t, but when it comes to tales of mistaken identity, mishearing, unexpected visits and so on, Cooney has no equal, certainly in terms of box-office success. His play Run for Your Wife showed in the West End for an incredible nine years and was performed in New York. Chase Me Comrade ran for three years.

Now his latest offering, a re-staging of the 1990 Olivier award-winning Out of Order (featuring a junior minister and an attempt at an affair with a typist) is touring Scotland from next week, and audiences will pour out to see it.

But how has Cooney managed to produce so much comedy madness? The bright trousers and blue shirt the 85-year-old wears today suggest an energy, and perhaps a little devilment about the man.

He certainly lives for theatre. “I love it,” he says in a quiet corner of the quaint Richmond Theatre in West London, where he appeared as a child actor. “It’s given me a fabulous life.”

He certainly loves writing farce. But in explaining his process, he reveals he doesn’t – at least not to begin with – worry over ways in which to disrobe his actors. “I don’t set out to write funny plays," he says. "What I start with is close to tragedy. Run for Your Wife, for example, is about a bigamist taxi driver. I start with a tragedy like this and work from there. If Ibsen got hold of that idea it would turn out very differently indeed.”

Cooney reads newspapers for ideas, noting how politicians are particularly inclined to stray from their loved ones. “Then what I’ll do is make notes. And once I have a year’s worth of notes, I’ll take them out of my pockets and drawers, bundle them up and go up to the attic and write every day for about six months.”

Cooney writes with a pen. No laptops for him – it's a Biro every time. “When I did my national service I was a typist in the Royal Army Service Corps. But I need the pen to make the connection with the paper. Then I’m into that world.”

In coming up with Run for Your Wife, Cooney found himself in his attic one day writing the line, "Here’s your cup of tea, darling." “I thought the character on the page was actually talking to me. Then when I looked around my wife was standing there offering me a cup of tea.” Linda Cooney understands her husband implicitly. Married to Cooney for 55 years, she was an actress who appeared in One for the Pot, the 1959 play he co-wrote with Tony Hilton (“Now she’s an artist. A very good one”).

Cooney’s work on a play doesn’t end in the attic. “After that, we do the workshops. With Funny Money [in 1995], for example, the workshop revealed to me the second act just fizzled away. The problem was I’d already committed to a try out in four weeks time in Guildford so I sat down and rewrote the entire second act in a month. Neil Simon would have been proud.”

Simon, the creator of such classics as The Odd Couple, once wrote of the pressure of deadlines heaped upon him by impatient producers, anxious for the delivery of the next (hopefully) smash hit.

“I’ve never succumbed to any pressure like that,” says Cooney. “It’s partly because I’ve produced my own plays so often. I don’t feel under pressure to write to deadline. I write because I love it.”

Cooney’s success suggests that as a young man he was desperate to become a writer, but Raymond George Alfred Cooney was nothing of the sort.

“I wanted to act from the age of 14,” he recalls. “All I ever wanted to be was Marlon Brando or Danny Kaye. So I answered an ad in The Stage to join a company in Cardiff, or at least I thought it was in Cardiff. It turned out it was in a nearby village, and was set in a village hall. We did a different play every night of the week, with a repertoire of 50 plays, and we’d tour the Welsh villages. I just soaked it all up. I loved this touring company and I’d have stayed with them, but they went broke when television came in.”

Cooney appeared in almost 200 plays in rep as a young actor, learning much about writing by osmosis. But the turning point in his life came in 1958 when he joined Brian Rix Productions in London’s Whitehall Theatre in a show called Simple Spymen, cast alongside Andrew Sachs and Joan Sanderson of Please Sir! fame.

“A run-of-play contract was exactly that, whatever the length ran to,” he recalls of his stint. “I could see this one would follow in the direction of Brian’s last play. It would run for years.”

To most actors, the virtual guarantee of nights working in theatre would have been a godsend. But not this one. “I decided I could no longer spend my days chasing girls and playing tennis.” Why not, Ray? That seems a perfectly pleasurable way to go about one’s day. “Not for ever,” he says, smiling. “But with all this time on my hands during the day, and Brian’s enthusiasm and help, another actor and I decided to try to write a play.”

It had to be a farce, given his milieu, and the result was One for the Pot. But what made Cooney think he could write? “I honestly don’t know,” he admits. “I guess I felt I must have soaked up so much from being in the theatre all these years, which I loved, so I’d have a go at writing a play, for Brian.”

Cooney’s success suggests it all came rather easily, but that wasn’t the case at all. “Neil Simon says plays aren’t written, they’re rewritten. And that’s the case. We kept taking our play to different theatres for try-outs and we’d rewrite it each time.”

He worked on his model. Start with tragedy, end in chaos. Use lots of stereotypes; husbands are browbeaten, Frenchmen randy, mother-in-laws suspicious dragons and gay men invariably mincing. But women almost always come off best; the men lose their dignity along with their trousers.

Another rule was don’t cast comedians. “You don’t want comedians in farce, although Roy Hudd and Terry Scott were good in the plays,” he says. “In my plays you begin with pleasant chuckles and then it builds up, you hope, to big laughs. But if you put a comedian in a play, they start to panic if there aren’t laughs in the first 10 seconds and they pull faces. You need people to play it absolutely truthfully – let the audience find the laughs.”

Cooney wouldn’t put up with corpsing, the likes of which you see in TV farce Mrs Brown’s Boys (“It’s a very funny show but you wonder why he doesn’t emphasise more dramatic plot lines”). His actors have to remain straight-faced. “Trevor Bannister [Mr Lucas in Are You Being Served?] would carry a four-inch nail in the palm of his hand to stop himself corpsing. But he sometimes failed. I can remember once seeing the blood drip from his hand.”

The farceur’s formula worked. The hits kept coming. After One for the Pot Cooney wrote Chase Me Comrade in 1965, inspired by the Rudolf Nureyev defection story. It was another massive hit, an Australian tour of which starred Stanley Baxter.

But what did Brian Rix think when his protege, as Mel Brooks once said of Gene Wilder, "opened up a grocery shop across the street"? “We never fell out,” says Cooney. “He was great. And what I learned from Brian is that the theatre demands you work as a team. Perhaps that applies to life as well.”

Cooney went on to become a successful theatre director, working with the likes of Peter O’Toole in Pygmalion. “We hit it off really well. I learned a lot from him and actors such as Donald Sinden, who would come into the theatre every night and go round every dressing room saying, ‘We’re going to have a wonderful night tonight.’ He created a terrific atmosphere.”

Farce still packs theatres, evidenced by the likes of One Man, Two Guvnors, an adaptation of the 18th-century Italian play Servant of Two Masters. Yet there are arguments that farce is too silly to be taken seriously by working-class audiences, that it essentially appeals to the frivolous middle-class sensibility.

“I’ve never thought about that,” says Cooney, looking surprised, “but I really don’t know. I’m just pleased if the theatre is nice and full.”

Pleased doesn’t tell the half of it. Cooney turned to producing plays and put his money where his Biro was. “I borrowed money from my mother’s burial fund, my wife sold her earrings and we put the money into a show,” he recalls. And he went on to make – and lose – millions over the years, either producing or running his own theatre.

He certainly lost the money he put into the 2013 film of Run for Your Wife, starring Danny Dyer and Denise Van Outen, which took just £700 in its opening weekend. “I think the mistake was in showing it to the critics at a private screening. We should have shown it before a public audience who would have been howling with laughter. But bad reviews are something you just have to deal with. And we had great fun making the film.”

The loss shouldn’t suggest Ray Cooney’s bank balance has followed the adulterous boyfriends in his plays out the back window. The writer lives in a lovely house in Epping Forest, just a kick of a ball away from Sir Rod Stewart and round the corner from Bradley Walsh. “I’ve been so fortunate in that the plays are being performed all over the world, in China, Russia, Japan. The royalties keep on coming in.”

He adds, with an appreciative smile, “Russia, you know, is the best country for paying royalties. India doesn’t pay. I once got a letter from a chap in Bombay. 'Dear Mr Cooney, I want you to know Run for Your Wife has been our biggest success ever with 1,000 performances. We are so thankful. I enclose my gift to you.’ The gift was a scarf and a box of marshmallows. It shows you how marvellous, Russia, Japan and China are.”

Ray Cooney loves his life and it’s not hard to see why. He has a great marriage and although his two sons and grandchildren live in Los Angeles and Sydney (“We go round the world every year to see them”) he’s been able to work in every area of theatre – acting, writing, directing and producing. “My life has all been about segueing from one thing to another. Now I can live off the lovely royalties and I support younger producers.”

But although he’s a Neil Simon fan, he hasn’t followed the New Yorker into sentimentality. “Neil can throw in moments of crying, as does Alan Ayckbourn, but I don’t go down the crying route at all.” Has he been tempted to try? “No, not at all, although I’ve been involved in a couple of musicals with a gentler side.”

As sure as living room doors in farce will open and shut repeatedly, Cooney has no plans to put his feet up. “I love both acting and writing,” he maintains, smiling. “Standing at the back of the auditorium hearing the applause is fantastic. And very rarely do theatre people retire. You either flop dead or go mad.”

Out Of Order, starring Sean Williamson, Sue Holderness, Susie Amy, James Holmes and Arthur Bostrom, is at the Theatre Royal, Glasgow, April 18-22.