In his latest role at Hampstead Theatre, Roger Allam plays a cantankerous former novelist all too happy to destroy the hopes and pretences of those who gather at his feet for advice. As a star of both stage and screen, with three Olivier Awards to his name, the actor in real life would surely be a valuable mentor for any aspiring thespian.

More so than the brutal tutor he’ll be portraying in Seminar until November, Allam still emits an undimmed romance for his craft – a love which stems from his days as a “rather lost” student thumbing through a book of classic actors such as John Gielgud, Ralph Richardson, Sybil Thorndike and Edith Evans.

That’s not to say he’s willing to dedicate his whole life to it, however. Married with two children, and now 60 years old, he admires the Daniel Day-Lewis approach of method acting, but isn’t one to bring his characters home with him.

“Over the years, when I’ve watched my two boys play,” Allam explains, “they play a lot of imaginative games together in which there’ll be acting; they’ll pretend to be someone else. While they’re in it, they’ll break off and say, ‘No, no, let’s do it this way, more like that’, and change the direction of the story.

“In a very sophisticated way, which I think is very natural to the way human beings play – which is, of course, what the theatre is, it’s the word for it, ‘play’ – we are able to both be in something and take it terribly seriously and then step out of it suddenly.”

Drag queen

A willingness to transform is the peculiar ability of any great actor and over the years it’s seen Allam play everyone from Macbeth to an army captain in drag.

In fact, it was the latter role (in Privates on Parade) that last saw him team up with Terry Johnson, the director overseeing this latest stage adaptation of Theresa Rebeck’s comedy.

A cocktail of ambition, power and lust, Seminar sees four young writers paying big bucks to compete for the approval of Allam’s Leonard – a figure based on real-life writer and editor Gordon Lish.

Although Leonard – previously played by Alan Rickman, who Allam spoke to for advice on the role – cuts an intimidating figure, his hostile approach is all for the sake of finding clarity.

“His method of teaching is to, I suppose, through criticism destroy the fabricated kind of beliefs that these [writers] have. You do seek that from a teacher: you seek someone to tell you the truth, but the truth is sometimes quite hard, rather than just to say ‘That’s really good’.

“A lot of what we think of as writing is quite a solitary craft, so it must be quite difficult to be in a situation in which you read something and you have to have an opinion and be critical, or encouraging. It’s difficult because there’s such a lot of carefulness and politeness that stops people telling the truth, when often the truth would be more useful.”

The idea of writing itself has rarely appealed to Allam, and he struggles to think of any mentors who truly laid down the law in his early years. In fact, when trying to chart his career progression, he finds it hard to narrow down any particular role that really “catapulted” him to fame – even ruling out stints in blockbusters such as Les Misérables and his Olivier-winning performances in Privates on Parade and Henry IV Parts 1 and 2.

“Winning an Oscar means immediately your price goes up, “he laughs, “which winning an Olivier doesn’t, or certainly not in my case.”

Having recently appeared in hit television shows such as The Thick Of It and Game Of Thrones, he admits to also occasionally “whoring” himself for the occasional advert voiceover.

Ultimately, however, he believes that, with a new generation of actors now growing up in a golden age of television drama, it’s another exciting time and one almost unrecognisable from the world that he grew up in.

“I wouldn’t know how to advise a young actor now, because the whole business has completely changed. When I started, you could actually get a job with a fringe company that would be paid above the Equity minimum, rather than having to work in little theatres for a share of the profits, ie nothing. You could still just about, when I was starting, get a season of work in a repertory company; I don’t know if any regional theatres do that anymore.

“In a sense, I still got a little taste briefly of what it was like to build up experience of acting in what used to be called ‘decent obscurity’, whereas now I think they have to be much more on the ball and be prepared to chance their arm and go out to the States to see if they can make it in the beast of American television. I think they’re rather remarkable, really.”

Roger Allam stars in Seminar at Hampstead Theatre until November 1. Visit hampsteadtheatre.com.