Sugar Daddies is a dark comedy by Alan Ayckbourn first staged at Scarborough 10 years ago which, after the initial tour, has rather disappeared from view. This new Harrogate Theatre/Oldham Coliseum co-production shows it to be well worth reviving, with Ayckbourn’s usual ability to make the unexpected seem real, even if it’s not in the first rank of his plays.

At the centre of the play is the relationship between Sasha and Val. She is a kindly innocent of a country girl sharing a flat in London with her older half-sister and studying at catering college. He is 70-plus years old, a former gangster and pimp who is still capable of calling in a few favours. She proves his Good Samaritan when he is knocked down by a car on the pavement while returning from his annual good deed – acting as Father Christmas at a local hospital. A loving friendship develops, with “Uncle” Val showering gifts on Sasha.

The revelation that the gentle old man is not what he seems comes fairly early in the play, but how will Ayckbourn take it from there? The two obvious and very different alternatives are for Sasha to be sexually corrupted or for the neurotic fears of her stressed out sister Chloe to be totally groundless, but this is Ayckbourn, so he takes a third course, ingenious and often unexpected, with some acute insights into what he calls “the gentle art of self-deception”. However, by his elevated standards, some of the plotting is a bit clunky and in particular he ties it all up in too neat a resolution, too easily achieved.

Director Robin Herford, long experienced in the plays of the Scarborough Master, finds the necessary ambiguity of tone, but the production has yet to settle into its natural rhythm: an over-run of 15 minutes from the scheduled timing suggests it will need a few more performances to hit its stride. In every way the play is about changes and contrasts and Michael Holt’s designs work well with the amiably untidy flat of Act 1 replaced by the expensively hideous product of “Uncle” Val’s generosity in Act 2.

As Sasha Sarah Vezmar exudes naive charm at the outset and remains convincingly the same person whether in a temper tantrum, a vain pursuit of social class or a winsomely sad little song. Paul Webster(Val) keeps the East End gangster barely in view beneath the kind old uncle, before enjoying his Ray Winstone moment under the influence of too much classy wine. Maeve Larkin’s Chloe is a vivid depiction of seven kinds of stress, Christopher Wilkinson offers a mirror image (often a distorting mirror) of Val as Ashley, Sasha’s other elderly admirer, and Heather Phoenix provides a lively cameo as Charmaine, once one of Val’s call-girls, now a “designer” of flats that look more like high-class brothels.

Sugar Daddies continues at the Harrogate Theatre until 9 March. For further information visit www.harrogatetheatre.co.uk