Les Liaisons Dangereuses was the Lady Chatterley’s Lover of its day. Published in 1782, the novel by the French army general Pierre Choderlos de Laclos was the racy book everyone wanted to read — even as they were swift to condemn the morals of the two protagonists and their quest for easy sex.

The Vicomte de Valmont and the Marquise de Merteuil were examples of pre-revolutionary French aristocracy at its most decadent. With nothing better to do than seduce young courtiers — the more innocent and saintly the better — they aroused a prurient fascination among an eager readership.

The book was considered too steamy for the public good and was banned in France in 1815. As Dr Katharine Swarbrick says in her programme note for the Royal Lyceum’s handsome production: “Despite the fact that

the two irredeemable debauchees who drive the plot come to a justly sticky end, it was considered that the moral of the story was not why people were reading.”

No doubt that’s true, but what strikes you in Christopher Hampton’s 1985 stage adaptation (the basis of the John Malkovich/ Glenn Close movie Dangerous Liaisons) is that underpinning all the licentious behaviour is a conventional love story with a surprisingly traditional moral heart.

It’s not the kind of play that differs much from production to production — Hampton’s witticisms and tight plotting make it pretty failsafe — but what John Dove’s staging has on its side is the clarity of the acting, the brisk efficiency of Michael Taylor’s open-backed set and a 10-strong ensemble with no weak links.

As Valmont, Dugald Bruce-Lockhart continues where he left off as Mephistopheles in the Royal Lyceum’s recent Faust, playing the suave seducer who revels in his own wickedness without being quite as callous as he’d like to believe. He is naturally handsome and charming, which makes his cynical overtures towards Siobhan Reilly’s wide-eyed and virginal Cécile seem all the more corrupt.

Tilly Blackwood as Merteuil — a self-styled “virtuoso of deceit” — has tremendous command of the stage, managing to be at once playful and ruthless, seductive and icy. Perhaps we don’t fully buy into the urgency of the sexual attraction between Valmont and Merteuil, but as cerebral sparring partners they make a sharp, waspish team.

Together they are like the opposing king and queen in a life-sized game of chess, idly sacrificing pawns before taking on pieces of higher value. The end comes when Valmont reaches stalemate, torn between his intellectual loyalty to Merteuil and his unexpected passion for the deeply orthodox Madame de Tourvel, whom he has seduced as a bet.

In that austere role, Candida Benson gives a stand-out performance, brilliantly conveying the whirlwind of passion that Valmont has stirred inside her without once breaking her straight-backed decorum. Tall, elegant and expressive, she shows how this respectable lady is too proper to give in to Valmont’s overtures, yet too nice to be cruel to him, her face in constant flux at she copes with the contradictory impulses driving her from bewilderment to fury to lust.

Such frisky costume drama has a bourgeois appeal — anyone for frock’n’roll? — but Dove understands there are archetypal forces at play that make Les Liaisons Dangereuses more than an irrelevant parade of French fops at their leisure. Valmont and Merteuil might behave with the cold-hearted indifference of the modern-day sex tourist, but it’s their love for each other that carries the play.

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