My Policeman By Bethan Roberts

Bethan Roberts's My Policeman was initially billed by its publisher as a novel inspired by E M Forster's relationship with a married constable, Bob Buckingham. Now it appears shorn of any reference to the author of A Passage to India, and it soon becomes clear why. Roberts's account of a polysexual ménage à trois has not simply been transposed to Brighton, but reimagined as a very different story. It is more obviously informed by Peter Wildeblood's Against the Law: the 1955 account of being prosecuted for homosexuality.

Its protagonist Patrick runs Brighton's Art Gallery, and has very different tastes to Forster; he re-reads Agatha Christie novels. In penning the indiscreet 1950s journals, he contrasts sharply with the cautious novelist, whose allusions to sexual partners were either coded in his journals, or locked away, or both. As a result of Patrick's rashness, and an impetuous act by Marion, rival for the policeman's affections, he is indicted for gross indecency.

Roberts deploys her research carefully, honing a novel with a strong period feel and a sprightly structure. It alternates between Patrick's record of his affair with PC Tom Burgess and Tom's wife Marion's memoir, written 40 years later.

The debt to sources, however, can be too pronounced. Conversely, some imaginary details prove far-fetched, such as Patrick's description of his lover's "lovely Brighton accent" as "very non-U". The reference to Nancy Mitford's 1956 volume Noblesse Oblige fits the period, but his distinction in class terms is wrong.

But many details are spot-on: Patrick's decision to befriend Marion before Tom proposes to her, to conserve "a crumb of him" for himself; his euphemistic references to homosexuality and rich period slang.

I wasn't convinced by the melodrama of the conclusion but the novel does capture the enforced evasiveness practised before the partial decriminalisation of gay sex in 1967. Forster himself was happy to write to a newspaper concerning the legal reforms recommended by the Wolfenden Report – but in support of the honour of the "married women" who did likewise. His lunch with its author remained a secret.