IT’S EASY to forget that Tom Stoppard was born Czechoslovakian, partly because he uses the English language with matchless bravura, partly because he has written just one television play, Professional Foul, about his native country. So what gives his new Rock ’n’ Roll special interest is that it’s a thoroughgoing reminder of his origins. Part of the play is set in Cambridge, but the best of it in Prague between the overthrow of Dubcek in 1968 and the aftermath of the Velvet Revolution in 1989.

The protagonist is Jan, a young academic sent to Britain to snoop for Czechoslovakia but too much of a maverick and too little the communist to please the spymasters. Back home he keeps his head down and indulges his passion, which is listening to his rock ’n’ roll records, but his avid support of a group, improbably called The Plastic People of the Universe, lands him in dead-end jobs and in prison as a “parasite”. And it’s a journey that brings a superb performance from Rufus Sewell: now spry, now frantic, now defeated, then quietly, movingly resilient and always the heart of Stoppard’s fascinating play and Trevor Nunn’s finely acted production.

What’s the point? That will keep real-life academics busy for years, but, for me, it’s mainly to be found in rock ’n’ roll itself.

We hear snatches of songs from groups ranging from the Pink Floyd to U2, the Doors to the Stones and Mick Jagger, who last night sat beaming in the central stalls.

We think that Czechoslovakia changed because of the efforts of Vaclav Havel and the likes of Jan’s earnest friend, Peter Sullivan’s Ferdy, and so it did. But let’s not forget rock ’n’ roll, a demotic, apolitical form that infuriated the cops, inspirited the young and showed the chasm between leaders and led.

Elsewhere, too, Stoppard seems to be decrying reason and exalting the passions. Hence his seemingly irrelevant invocations both of the great god Pan and of the first poet to celebrate erotic desire, Sappho.

And hence the play’s sub-plot or co-plot, which involves Brian Cox as a Cambridge communist who clings to marxism like a barnacle to a rusting ship and Sinead Cusack as his cancer-ridden wife, who finds his materalistic, mechanistic views a cruel insult to herself, human mystery and the world’s complexity.

Towards the end, the play itself seems over-complex and over-busy (please tell me why must we bother with the emotional intricacies of Cox’s granddaughter and the rest of his family?). But never mind. Cusack’s fervent plea still rings round my head: “I am not your amazing biological machine. I am not my body. My body is nothing without me.” It could be Sir Tom himself speaking. For him, it’s the spirit of a person, of a person that truly counts — and in Rock ‘n’ Roll, the soul of a nation that matters too.

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