This play by Terence Rattigan has not been seen in London since it was a hit in 1944. Indeed, this version has never been seen since it combines the playwright's first version of the play, titled Less Than Kind, with his second, Love in Idleness, which was rewritten to make it a better starring vehicle for the hugely popular American husband and wife acting team of Lynn Fontanne and Alfred Lunt, known as the Lunts.

You can see the compromises glinting through this sparkling and reminted production directed with scrupulous care and considerable style by Trevor Nunn. The play tells of the havoc wrought when Michael Brown, the son who has been sent to Canada for safety for the duration of the war returns home to find his widowed mother Olivia living in unmarried and luxurious bliss with the Canadian industrialist and Cabinet minister Sir John Fletcher.

Despite all Olivia's vain pretence, Michael is now 17 years and 11 months old and with a mind of his own; he immediately takes against Sir John, not only because he resents his relationship with his mother, but because, as a left-wing firebrand, he rejects everything the older man stands for. "You're a stinking reactionary," he tells him, fiercely. Olivia is torn; she loves Sir John and her pampered, unworthy life. But she also loves her son and his vision of a future where workers are rewarded for their labours, and the world is fair, even if that means living in an uncomfortable bedsit.

The Lunts asked Rattigan for a rewrite because they wanted more fun and less politics; in bringing the versions together, this new Love in Idleness plays like a farce with ideas attached. But it doesn't matter because Rattigan does what he does in other greater plays: he portrays such depth of feeling that the story is suddenly rooted in something so movingly truthful that it transforms a lightweight comedy into a universally relevant observation of parents and children and the problems of finding true, true love.

In mining this profound vein, Nunn skilfully emphasises that the political arguments are real, that the battle between Michael's idealism and Sir John's belief that the new world will be "the same as the old world but spring cleaned a little" is one worth arguing about by linking each scene with newsreel footage of very different and more socially committed times. Yet he also lets Michael's outbursts – and his tendency to play Hamlet at every turn – become part of his adolescent angst. When he flings himself face down on his bed in despair, everyone in the room can recognise the agony of growing up.

The whole thing is performed with a real sense of period tone and comic timing but also with finely calibrated sense of the powerful emotions at work. As Michael, Edward Bluemel perfectly captures the confusion of youth; there is some clever business with a cigarette that his mother keeps taking out of his mouth that underlines the way he is just on the cusp of adulthood. Anthony Head as Sir John is equally adept and perfectly poised, exasperated by this "odious little rat" but desperately trying to hold on to the woman he loves and Helen George's appearance as his estranged wife is an all-too brief and blazing turn of ditziness. Her wide-eyed surprise at finding herself in her husband's flat is a joy to behold.

But it is Eve Best as Olivia who grounds the entire thing. It is not easy to play this kind of hare-brained and affected woman and make you care `about her. Indeed her opening lines, lounging on a sofa in silk pyjamas and screeching "Hello Dickie" into a telephone, more or less explain the contempt in which Rattigan's drawing room comedies were held by John Osborne and the kitchen-sink dramatists who followed.

But Best reveals the complexity beneath the frivolous façade; forced to make a choice between lover and son she is heartbreaking, clutching her child to her in an unbreakable hug, trying to hide despair beneath small talk. She walks the tightrope of the play without a wobble, revealing if not quite vintage Rattigan still a play well-worth rediscovering.

Love in Idleness runs at the Menier Chocolate Factory until 29 April.