Don't mention the L-word, you're warned before interviewing James Bolam. The actor who played the incorrigibly laddish Terry Collier in The Likely Lads is apparently loath to discuss anything about Dick Clement and Ian La Frenais's classic sitcom. Emboldened by Bolam's twinkly manner, however, I took courage and brought up the unmentionable over lunch with him last week. I lived to tell the tale.

At first it looked like I wouldn't, as he frostily declared that he never bothers to watch the re-runs which are doing so much to make him popular with a whole new generation. "It's something I did 25 years ago," he harrumphed. "Do I want to see how I was then? No, thank you. It's depressing enough to see how I am now."

Then he pooh-poohed the idea that he might keep in touch with his co- star Rodney Bewes, who played Bob Ferris, the other Likely Lad. "Why should I?" he asked. "In this business, you do one job and then move on. You wipe everything else out - you have to. You can't live in the past."

But he melted before you could say, "What became of the people we used to be?" Smiling slowly over his plate of spaghetti in a central London restaurant, Bolam soon proved more than happy to talk about the role he is still most famous for. "The Likely Lads has lasted because the characters struck reality," he reckoned. "People could identify with them. Mothers could identify with sons, and sons could identify with themselves.

"The series works so well because there's an underlying truth about it all," he continued, suddenly and unexpectedly warming to his theme. "That's why classics are classics. When you watch Laurel and Hardy, there's a fundamental truth about them, a believability which I never find with Chaplin. In the same way, you can believe in Bob and Terry."

Bolam's one worry has always been that he will be typecast as Terry. "That's always a danger," he nodded. "In those days, if you did an ad, you were persona non grata. Now you do an ad, and you get a series out of it."

Over the years, Bolam has been associated with some of the best writing television viewers can buy - from The Likely Lads, through When the Boat Comes In to The Beiderbecke Affair. He is concerned that original writing of this quality is becoming a seriously endangered species. "Things get turned down now because the TV companies feel they won't get the ratings," he lamented. "Producers don't want to make a mistake, so they just do what everyone else does. People won't take risks as much as they did. The BBC used to produce terrible things as well as wonderful things. You have to have the licence to make a fool of yourself."

A fit 59-year-old, Bolam is still very much in demand. He has already played leading roles in two successful BBC1 dramas this year - Have Your Cake and The Missing Postman (released this week on video). Producers like his sure presence on screen. "I'm quite singular and strong in my approach," he confirmed. "I tend to know what's required. A lesson I've learnt over the years is that you can only do one thing at a time. Too many actors try to do too much and end up falling between two stools. That's why I like directing [he has mounted several successful theatrical productions]. You can say to the audience, `There's where you watch'. If you have too much going on, it confuses them."

He is soon to appear as an out-and-out psycho in a one-off TV drama, The Stalker's Apprentice. "Evil guys are not hard to get into," he said, with relish. "Baddies are always much more fun. Goodies tend to be reactive, whereas baddies tend to make things happen."

A modest, unassuming man, Bolam has long shunned the limelight - he was granting me a rare interview. As we parted, he reflected on his past reticence with the press. "One should be judged not by what one is, but by what one does," he mused. "Also, the media encourage the notion that you are like your parts. Does that mean that you can't play Macbeth unless you go out and murder someone, or that you can only play Hamlet if you don't like your mother? It's just acting."

`Whatever Happened to the Likely Lads' is on BBC2 at 9pm tonight. A BBC video of it will be released next month. `The Missing Postman' is released this week on BBC Video. `The Stalker's Apprentice' will be on Bravo in October