Denis Lawson on bringing Glaswegian grit to BBC hit New Tricks

"I don't know how I ever built a career, really, because I have always been absolutely terrible at auditions," he confides. "There is a certain Scottish hubris kicks in. I just think, 'Well, if you can't see what I've got, then I'm not going to put myself out for you.' Come on, surely they know what I can do by now."

Relentlessly upbeat, charming and chatty, Lawson, who lives in north London, is easy to warm to. He's quick to laugh, disarmingly honest and thoughtful. We are supposed to be talking about the return of New Tricks, BBC One's ratings hit. Lawson joined the cast of the police show in 2012, in which a troupe of ageing detectives revisit old cases and prove that experience trumps modern policing methods. But it takes 45 minutes before the programme crops up in the conversation. "We should probably give that a quick mention," he concedes.

Before that, in precise, clipped, staccato sentences, Lawson ponders his childhood, and why acting was such an unlikely career choice. "My family are all Glasgow. I was born there. Govan. When it was very tough. The tenements. All that stuff," he says.

A move to Crieff at the age of three gave him access to the rolling countryside, and he recalls playing out in the street until darkness fell.

But it was on trips to the city of his birth to visit his grandparents that Lawson was inspired to follow his early heroes, Jerry Lewis and Gene Kelly, on to the silver screen.

"We used to go through when I was about eight to see variety shows," says Lawson. "That was a huge influence. My initial impulse was to be an entertainer, a song and dance man."

The other major influence on Lawson was his mother, Phyllis, who still lives in Crieff and only retired from the watchmakers she ran with Lawson's late father, Laurie, in 2006.

"My mother was a dancer when she was a kid and I gather she was very good, but was never allowed to go into the profession," he says. "Although I never remember her going on about it. She used to teach us little dances, my sister Carol and I, which was great. That was our only vague connection to showbusiness, and yet it came out so strongly in me."

It wasn't until he began to see his own background reflected on the big screen in the early 1960s, and he heard about something exotic called a drama school, that Lawson considered serious acting as a career. "There was a big change going on, with working-class actors like Tom Courteney and Albert Finney coming up," he recalls. "Culturally, things had shifted after the war. Most actors up until that point had been, or at least sounded, upper class. Suddenly there was a whole groundswell of writing, largely coming out of the Royal Court in London, of working-class or lower middle-class drama. It was called 'kitchen sink' at the time, and those actors and writers really did have a big impact.

"My background is essentially lower middle class, and when I saw these guys, it was immediate. They made it seem possible."

Getting into drama school at the second attempt in Glasgow (now the Royal Conservatoire of Scotland), Lawson recalls the "vibrant, gutsy" city and the pure joy of being able to act, after yearning to do so for such a long time. So how did his parents react to their son's thespian leanings?

"I was never discouraged. But it was a bit leftfield, and I'm sure my parents were quietly worried," he says. "I do remember my father once having a conversation with me about maybe joining the army. But what was fantastic was that the first production they ever saw me do at Glasgow, which was Under Milk Wood at the end of my first year, they were just knocked out by it. They realised what I was doing was serious and were 100 per cent behind me from then on."

Lawson continued learning once his schooldays were over. His second TV role was alongside the greatest British actor of his and perhaps any generation. "He wasn't bad; I picked up a couple of things from him," Lawson laughs, recalling playing Lancelot Gobo to Laurence Olivier's Shylock in a BBC production of The Merchant Of Venice in 1973.

"Olivier had this line to me: 'You are a huge gormandiser,'" Lawson continues. "I was standing on set one day, and casually asked him: 'What is gormandiser, by the way?' He didn't make a big deal of it, he just told me that it meant a glutton, but I got home and realised it was appalling. This line was about my character and I didn't even know what it meant. Ever since then I have always read a play or any script with a dictionary by my elbow."

This is just one of the tips Lawson passes on in his new book The Actor And The Camera. He describes it as a technical book for actors, full of the nuts and bolts of filmmaking - hitting your mark, getting eye-lines right, how the camera works, what everyone on a film unit actually does.

"These things take years to figure out, because nobody ever tells us," he says. "The result is that you stagger along for ages trying to look like you know what you're doing.

"It is not a memoir. There are references to very good film actors I have worked with and what I learnt from them. But it is not me saying, 'I remember the day on the set when we had a lovely lunch …'"

So why, when his career in front of the camera continues to flourish, did Lawson feel the need to put pen to paper? Two things, he says - one relating to one of his finest films, the other to his famous nephew.

"I was shooting Local Hero on the beach up in Camusdarach on the west coast. I was standing by the camera as they were reloading the film and had this small epiphany. I realised I had no idea what went on with this piece of machinery, and yet this was where my performance was going - into this black box. From that moment on, I started asking lots of questions.

"But the big impetus was years later when Ewan [McGregor] was in his final year at Guildhall in London. He was leaving to do the Dennis Potter series Lipstick On Your Collar and came over to the house. I'll never forget his phrase. He said: 'I've got this incredible job. What happens?'

"Here was a fantastic young actor from one of the best drama schools in the UK and he had absolutely no idea what happened on a film set. Not a clue. So we went upstairs, and I talked to him.

"I threw a sock on the floor and said: 'Give me a couple of lines, then walk towards me and end up with your feet just behind the sock. He tried it, but I had to tell him he couldn't look at the sock. It was the basics of hitting your mark. Simple stuff. Then he said: 'You have to come and talk to my year, because we don't know any of this.'

"I began to run occasional film workshops, because the fact is that the majority of actors leaving drama school now will end up working in front of the camera. They won't go on to the stage, much as they may like to."

More than four decades on from his West End debut in 1969, Lawson retains a boyish enthusiasm. He lists his early 1980s stage musicals Pal Joey and Mr Cinders, controversial 1985 TV thriller Dead Head, the BBC's Bafta-winning 2005 adaptation of Bleak House and the brilliant silent comedy episode of Inside No.9 and working with Charlie Chaplin's granddaughter, Oona Chaplin, among many highlights.

The conversation also keeps returning to Local Hero. "There are a couple of guys in Crieff who have taken over a disused library and are turning it into a cinema and music venue, The Strathearn Artspace. It is a brilliant idea for a place like Crieff," says Lawson, who is one of its patrons. "They are screening Local Hero on August 29, and I will be heading up there."

And a word on his co-star Peter Capaldi, who played local oil firm representative Danny Oldsen? "That was his first job as an actor - he was doing a warm-up act for rock bands at the time. And now he is Doctor Who - I will be watching. We are still great friends; he is terrific."

Yet despite all the good times it has given him, Lawson's advice for aspiring actors is stark. "The best thing to say to a young actor is: 'Don't do it,'" he says. "If you have any question in your mind, if there is any doubt, don't do it. It is too tough. There are a lot of brilliant people who don't get there."

Lawson talks with passion about the importance of enduring friendships in an often transient, up-and-down business, citing Zoe Wanamaker, Lyndsay Duncan and her husband Hilton McRae, and Joanna Lumley, his co-star in Sensitive Skin, as invaluable.

Lawson lost Sheila Gish, his wife and partner of more than 20 years, to cancer in 2005, and has spoken before of struggling with depression. He returns to the subject when he talks about acting on stage.

"There is something physical that happens, an adrenalin rush, particularly on stage and in the musicals I have done, and that is really quite extreme," he says. "Coming down from that is tough. At the end of a big job, I would often just go through the floor because it all stops. It can be so hard for the body and the mind to cope with that."

Between jobs, he likes to indulge his passion for music.

"I get withdrawal symptoms if I don't listen to live jazz," he says. "I have been going to Ronnie Scott's ever since I moved to London in the early 1970s. I've seen some amazing people. I grew up in a small market town and it is great to go up to Crieff, but it's one of the reasons I don't think I could live anywhere else."

Another solution to the post-job slump? The long-running regular drama. He enjoyed his time in Holby City, in which he was a regular from 2002 until 2004. "By the time I left, I was so plugged into the camera, and then I hit Bleak House, and was really on song for that role."

Now, he's starring as one of the oldest coppers in town, alongside the only remaining original New Tricks cast member, Dennis Waterman, plus Nicholas Lyndhurst and Tamzin Outhwaite.

"We have a lot of fun making it. Dennis Waterman and I have a great rapport," says Lawson. "When I came into New Tricks, the character was supposed to be from Birmingham. I really didn't want to be doing that accent for the next two years so I told them I wanted this guy to be from Glasgow. Very specifically Glasgow.

"I just thought it would be a really interesting cultural mix. Bringing that strong Glasgow personality down south. And the person it works with best is Dennis, who is so intrinsically London to his bootstraps.

"He does take the piss, though. I had never heard the expression 'sweaty' before to mean a Scotsman. Never heard it in my life: sweaty sock - Jock. It is not very complimentary, is it? But that joking is always there with Dennis."

For Lawson, the show's enduring appeal - to a much wider age range than many suspect - is down to a welcome touch of anarchy. "There is a big anti-establishment theme in the series that people really like," he says. "The baby boomers taking on the establishment. I constantly meet younger people who are totally hooked on it."

And, says the grateful actor, it allows him to return to his first love, from way back in the theatres of Glasgow in the 1950s. "I have always secretly thought of myself as a light entertainer, a comedian, going back to my music hall, vaudeville roots as a kid," says Lawson. "So it is nice to be able to be funny. I have not done enough of it on camera.

"I would love to be able to show off my song and dance moves as well. I am always on the look out for an all-singing, all-dancing series …" n

New Tricks returns to BBC One on August 18 at 9pm. The Actor And The Camera by Denis Lawson is published by Nick Hern Books, priced £10.99.