Anything Is Possible If You Think About It Hard Enough review – charming odd-couple courtship

Alex and Rupert should never have met. They certainly shouldn’t have fallen in love. But thanks to a quirk of fate – a magical aligning of numbers, as financer Rupert would put it – they bump into each other on the tube one morning. They tease and taunt, flirt and fight, fall for each other and eventually fall pregnant. Playwright Cordelia O’Neill keeps us laughing every step of the way, until suddenly the unthinkable happens to Alex and Rupert and then there is only silence.

In many ways (most of them good), Small Things Theatre company’s latest production is a good old-fashioned romantic comedy. It involves a classic mismatched couple, destined to either hate each other or fall madly in love. O’Neill absolutely nails the giddy energy of those early dates, when conversation tumbles all over the place and the thirst for knowledge about each other is all-consuming and unquenchable.

Huw Parmenter is brilliant as numbers man Rupert, who eats egg whites for breakfast and says words like “twerp” and “fiddlestick” without an ounce of embarrassment. Gemma Lawrence impresses as Alex, who is both utterly sure of herself, but lost and broken too. They’re great characters in their own right, but it’s when the two talk to each other that we’re utterly, cheek-warmingly charmed.

Director Kate Budgen sends Alex and Rupert whirling around the stage space in the early days of their courtship, folding the audience right into the heart of the action. Camilla Clarke’s set suggests a life on the verge of starting, with paint samples carefully dabbed on the walls and a big white bed that is first a happy place and then, later, a very sad one.

The moment of loss is met by a long silence that holds the audience in its awful clutch. But after this point – and there’s still roughly half the play to go – this lovely but relatively light script can’t sustain such a heavy load. The excellent dialogue is taken over by mawkish monologues and the exquisite detail of Alex and Rupert’s romance is blotted out by a shocking but strangely generic grief.

• At Southwark Playhouse, London, until 9 October.