Backseat Ian comes up front

Ian Hart has always been the Brit At The Back. He's a face we all know from somewhere, the unsung hero we can't quite place. Wasn't he John Lennon in Backbeat? Or was he Nobby Stiles in Best? If you didn't see the credits you probably wouldn't notice him. It's a measure of just how good an actor he is that half the time you don't realise that it is Ian Hart at all.

So far he has about three dozen films under his belt (as well as all the TV stuff - EastEnders' Mick, One Summer's Ian Davies), with two more opening in the next couple of weeks (gritty Thirties drama Liam and salsa comedy Born Romantic), and two in post-production (Peter Capaldi's Cocozzo's Way and thriller Killing Me Softly with Joseph Fiennes and Heather Graham). Then there's a major new production of his own, a six-week-old daughter.

As you read this he's probably still togged up in academic gowns finishing off the Harry Potter film somewhere in Gloucestershire, as Professor Quirrell, Dark Arts teacher to H. Potter. 'I nearly didn't get this role,' says Hart. 'When they sent me the script I'd not read the Harry Potter books so I went off to Waterstone's to buy the first one. But they gave me the second volume, which I settled down to read. About half a chapter in I thought, "Hang on, I've lost the plot here."'

As Quirrell he's enunciating his lines in old-fashioned RP accent ('received pronunciation like the Queen's speech used to be'), one of many in his stock of dialects such as an Irish brogue, Lancashire, Cheshire, Belfast, American, ex-public school. Normally it's regular, ripe Liverpudlian spoken at such speed it's sometimes incomprehensible. It's the accent he uses in life and, more or less, in Liam, a film by Stephen (High Fidelity) Frears and written by Jimmy (Cracker) McGovern.

Liam's a more familiar plot for Hart than Harry Potter - he plays the father of a little lad, Liam (played by the extraordinary Anthony Borrows), growing up in an Irish Catholic quarter of Liverpool in the depressed Thirties. Hard times hit the docks and Dad loses his job. Disenfranchised and broke he joins the local Fascists. 'We tend to look at fascism now in hindsight with World War Two and Hitler and Mussolini and so on but in the Thirties fascism was presented as a political alternative,' he explains. 'Instead of socialism Liam's father chose fascism - for a working-class man who loses his job it was an equally valid argument. He was seeing his family free-fall into poverty during the Depression. What else was he supposed to do?

'I have no particular political axe to grind. I haven't a lot of time for political parties. People say, "But you played an English communist fighting the fascists in Ken Loach's Land And Freedom." I just play the roles. I definitely don't do these jobs as a political platform. The script for Liam was fantastic. Land And Freedom was a wonderful part for me. I had no views on the Spanish Civil War before the film. Now I know I would have fought in it, and so, I think, would several of my friends. But then it was just a brilliant job.

'Liam was originally going to be a telly film for the BBC which is, in a way, a shame, because BBC television is a public service and this is quality drama. I'm not snobby towards TV but I think a great disservice has been done to us by dumbing down the BBC. The BBC now has to compete with ITV and Channel 4 for ratings and audiences. TV's great if your film has a message. It's all very well making films with a message and then expecting people to pay nine quid to see them. I know people should go to the pictures, but at what price?' He pauses. 'Anyway, most of my films never go beyond London for more than a few days!'

Ian Hart, 36, is a medium-looking sort of a bloke with blue eyes and a canny laugh. He can have the look of a jug-eared, wire-haired terrier for comedies such as This Year's Love, but also can be kept tightly on a leash in films such as The End Of The Affair, The Hollow Reed, The Englishman Who Went Up A Hill But Came Down A Mountain, Nothing Personal.

He doesn't come from a cinema background. He is one of three children, his father worked at the Ford factory in Halewood and his mother washed dishes part-time at a school kitchen. They lived on a council estate in the middle of nowhere. If there was a holiday it was to Wales, not Benidorm. He still goes to Wales for holidays and, nowadays, the Lake District as well. The nearest he got to the cinema as a kid was watching Kes, Loach's v?rit? film about a working-class lad in the North.

He went to a Catholic all-boys grammar school run by priests and nuns, was an altar boy, went to Rome and twice to Lourdes. 'I was a super Catholic in those days but became a rebel by the time I was about 12. I made myself unpopular with the nuns by arguing with the teachers. I must have been a pain in the arse.'