the interview MARK STRONG TALKS TO BEN THOMPSON

people who measure their lives in TV drama - who can tell you which particular rite of passage they underwent between Howard's Way and the first series of The House of Eliot - have a new staging post. Peter Flannery's Our Friends in the North, once enticingly trailed in BBC memoranda as "a drama about post-war housing policy", is already one of those small- screen happenings for which years get remembered. Not so much for the writer's ingenious attempt to weave 30 years of social history into nine co-incidence-packed episodes, as for the seductive unfolding of the inner lives of its four central characters.

Crag-faced Geordie, hyper-earnest Nicky, and Mary the resentful abbess all have their advocates, but Mark Strong's Tosker (ne Terry) Cox is the one who steals the show. Like Yosser Hughes in Boys From the Blackstuff, he starts out with the pronounced advantage of a first name ending in "er", but there is more to him than that. Tosker has carried himself with dignity intact through not just one but three of the most exquisitely embarrassing sex scenes in televisual screen history. And when he burst into tears on Monday, his lachrymosity was more heart-rending even than that of his fellow Tynesider Paul Gascoigne.

There is afternoon football on the TV in the pub wherein 32-year old Mark Strong lurks benignly. Stan Collymore is playing. He cost roughly the same as Our Friends in the North, and those who doubted he was a good buy are looking pretty silly now, too. Strong is drinking Guinness, and is careful to have no more than two. Not only because he is driving (a battered old white MG, which he describes self-effacingly as "a typical wanky actor's car") but also because the production he is heading off to Maida Vale to take part in after the interview - a Radio Four dramatisation of the Scott inquiry - just lost a cast member because someone could smell drink on their breath. Who said actors' lives were easy?

Strong is facing away from the pub door. Currently up for the lead role in the film version of Nick Hornby's Fever Pitch, he is watching the football with some attention. From the back, without one of the superb baroque hairpieces with which he has been routinely adorned as Tosker, Strong is elegantly dome-headed. When he turns round to say hello, he has eyes that parties of schoolchildren could go swimming in. He has no Newcastle accent, but the long hours of studying Auf Wiedersehen Pet videos have made it hard for him to essay any other local speech inflection apart from his own light London.

Born in Islington, Strong now lives with his girlfriend down the road in Newington Green, but there is nothing parochial about his background. His mum came from Austria and his dad was Italian - "They came to England in search of the Swinging Sixties," Strong explains, "but they didn't find them" - and he was originally christened Marco Giuseppe Salussolia. The name was Anglicized after Mark's mum divorced and remarried his English step-dad. They moved to Norfolk in search of "family life in the country", and after passing his 11 plus, Strong ended up at a large local state grammar school "in a field surrounded by another field". When his mum moved away to Germany, after her second marriage broke up, he was left behind as a boarder.

If he bears her any ill-will over this, he doesn't show it. "She was only 19 when she had me, which is much too young to be saddled with a baby really," he points out sympathetically. "She was just having a go." Strong got his mum a video of his hungover but charming recent appearance on Richard and Judy "which she was very pleased with." After eight years on the stage - progressing from provincial rep to the RSC to lead roles at the National Theatre - he now seems to be making a smooth transition into film and TV. Prime Suspect 3 was his first decent part: "I was the apparatchik copper being a bit cold shouldery to Helen Mirren at first but after a while liking her because she's a good policeman." Next came a textbook heavy with Tim Roth and Julia Ormond in Captives, and then the real breakthough: a year being Tosker.

The roguish North-Easterner is a character who elicits a broad range of reactions: from profound sympathy and affection to (and this seems to be quite widespread) "he's a bastard." "I didn't think he was a bastard," Strong insists. "I was really trying to play somebody whose life is constantly getting knocked back. At the beginning he's spoilt rotten by his mum and dad. He wants to be a rock and roller - he's got the amps, the guitar and the pub and everyone's proud of him and patting him on the back - but then everything goes horribly wrong. His girlfriend gets pregnant and he has to stop his apprenticeship, and then he gets laid off from his factory because they're busting sanctions, and then the flat starts getting damp and his marriage isn't quite what he thought it was going to be ..."

Tosker's marriage is an intriguing business. The clever wife who gets her academic wings and leaves her husband behind has become almost a stock figure in quality TV drama, from Brookside onwards, but Our Friends in the North puts a neat twist on this storyline. When Tosker accuses Mary of "ripping him off" - bettering herself at his expense without contributing anything in return - he is not wholly without justification. It is this that makes what Strong describes as the "ritual shag" which follows so agonising. "I think there were a few hot sofas around the country at that one," he observes, with an understandable sense of a job well done.

Tosker might easily have been flattened by the heavy symbolic burden he has to carry as the embodiment of a sense of place - "I think Nicky was the writer's political side, Geordie was his sex and drugs and rock 'n' roll side, and Tosker was his Newcastle side," Strong explains. It is to the credit of all concerned that he ended up neither ale-swilling Neanderthal nor paragon of proletarian virtue. "There's a kind of simpleness about him but that doesn't mean he's stupid," Strong says fondly, "and a kind of hardness but that doesn't mean he's not vulnerable. He's just someone who's working his bollocks off to do something and get somewhere despite all the limitations holding him in."

A very moving scene in the episode just gone found Tosker in a nightclub toilet, painstakingly plastering his thinning hair across his head before launching a half-hearted dancefloor charm offensive. Strong's own perspective on the process he jauntily terms "coming out as a baldie" is much more upbeat. "When I decided to crop what was left of my hair, I thought 'It's all over, I'm never going to work again: it's basket weaving me for me from now on.' But what actually happens is your casting changes: you suddenly start to get a lot of villains and coppers and soldiers and even the odd sensitive vicar - you become institutionalised."

Presumably that's a good thing for an actor. "It's great. You don't have to play lovers anymore: Ferdinands and Sebastians at the RSC, swanning around and spouting poetry." Strong positively beams. "It was a great day for me when my hair fell out."

Did it happen overnight? "It took a while. I never made the Bobby Charlton, but I wasn't far short of it. I remember walking across Waterloo Bridge to the National Theatre once and my hair sort of flew up like this [he demonstrates with an anguished wave of the hand above his head], and I just thought 'This is pathetic'. I'd even started to get a bad neck because I'd got really good at knowing where the wind was coming from."

There is little sign of Mark Strong's head being turned by success. "I'm not convinced that this business runs on talent," he asserts modestly, "otherwise why would there be so much crap on the box?" Hollywood "doesn't really appeal" at the moment, "though obviously if somebody rang up and said 'We'll give you a million dollars' I'd have to think about it." When he is not working, Strong practises mixing house records on his DJ turntables and puts up shelves. He once sent a pork pie with an "unmistakable" pubic hair in it back to a world-famous food store using one of Joe Orton's old pseudonyms.

He also once walked down Potters Bar high street in stack heels wearing a horrible 1970s tailored denim jacket with "punk" written across it. Now, though, he is ultimately sweet-natured. Strong's voice only acquires something approaching an edge on a single occasion, and that is when talk turns to his notoriously prickly co-star Christopher Ecclestone. It seems all was not entirely friendly in the north. "He didn't speak to me for the whole year we were filming," Strong complains. "At first I thought it was to do with the characters - because there was supposed to be tension between us, but then I realised" - he shakes his head in genuine bewilderment - "he just didn't like me."

8 'Our Friends in the North' continues Monday, 9pm, BBC2