"It's one of the attractions of acting," says Timothy West, "playing people who are more intelligent than you are and saying brighter things than you could ever have dreamt of.

Hilary is deeply intelligent, I think - a lot more so than me."

To hear West talk, thoughtfully and wittily, about the complex past he has imagined for his character, you'd hardly think him of average intelligence. But then there must be a particular satisfaction in acting a play by Alan Bennett - especially one described by Alec Guinness as: "The best English writing since the flowering of Evelyn Waugh."

Receiving its first major revival (courtesy of English Touring Theatre) since its premiere in 1977, The Old Country is a typically wry and bittersweet tale of fading memories, lost manners, and just what it means to be English.

Hilary (West) is an old British spy, now in exile in the Soviet Union. Surrounded by English books and Elgar, he and his long-suffering wife (Jean Marsh) seem to be stranded in a no-man's land.

Hilary's brother-in-law arrives, intent on persuading him to return home to the warm embrace of the English establishment - following a spell in prison, of course. Meanwhile, Eric, a young, much more ordinary kind of English spy, has come to visit with his KGB agent wife, hoping to blackmail his way home.

"I saw it in 1977 and loved it," says West. "It's a spy play and it rather fell under the shadow of Bennett's two other spy plays - the one about Burgess and the one about Blunt. It's a very different play from both of them, I think, and not just because it's not about a historically real person. It's also much more a play of ideas."

At the play's heart is Bennett's particular affection for, and criticism of, English institutions, filtered through the passionate ambivalence of his central character.

"Hilary's got this enormous collection of valuable books which you wonder whether he actually ever reads," explains West. "They're a kind of anchor to a Britain which he loves and remembers, but at the same time criticises, for its politics and for dealing with values that really have no real meaning in the world.

"At the end he complains that English literature is all about school in the trenches and death in vicarages, and the siege of the country house."

Directed by Stephen Unwin, The Old Country is set roughly at the time of its first staging, so West has worked out that Hilary would have grown up at the time of the Cambridge spies. "We tend to forget that, at the time, the Labour Party had terribly let us down," he says. "People who had socialist leanings were left in a sort of vacuum - they either went one way, towards Mosely and fascism, or the other way, towards Lenin and Communism. Hilary went the second way.

"The wit is Alan's best in many ways," he adds. "It doesn't sound terribly funny when I describe it but it's been getting very big laughs."

A very different experience from that of playing Lear, then - a role which West undertook for the company to massive acclaim in 2003.

"Lear in some ways is a much easier part," he says, laughing, "because he's active rather than proactive.

"Things happen to Lear, whereas Hilary creates his own dilemmas. This is more complex in a way because you're never quite sure - and perhaps he's never quite sure - what he thinks.

"He can change from line to line - and sometimes from night to night."