I’m not sure what the British record for bigamy is – it’s not the sort of thing that deserves to be celebrated – but Major Alexander “Alec” Wilson was surely one of the most mysterious of this strange breed. Mrs Wilson (BBC1) is the saga of the many women and children in his complicated life, one of subterfuge, layered upon fantasy, covered in lies. He was, certainly, a professional spy, but he inverted the usual convention by using his status as an agent to cover up his less honourable real lives, if you see what I mean. Iain Glen does well to play Wilson, as such a massive… enigma.

The sagas are told through the eyes of his second wife, Alison, played here by her actual granddaughter, Ruth Wilson (and, lest there be any doubt, she is also Alec’s granddaughter).

Ruth Wilson is superb throughout, and none more so than here, when, finally exhausted by the posthumous traumas Alexander puts her through as wave after wave of other wives and kids emerge without warning, she collapses. When she wakes, she leaves the family home forever, and finds solace in devoting her life to God as a nun.

The attention to period detail is doubly impressive, melding as it does the 1940s, when Alison was the young wartime bride and mum, and the 1960s, as widow and, indeed, victim. Through some clever direction, we, and Alison, could occasionally catch glimpses, cameos if you will, of the major’s other lives and other women.

They are all deftly done, these little examples of deception visited upon the audience. They make the point. Keeley Hawes, as Dorothy, is also excellent as Alec’s sultry cover story lover/real lover/wife in British India.

In one final twist, we leave the world of air raid sirens, Brylcreem and Austin motor cars, and land in 2018. We get to see a huge multi-Wilson family reunion of many of the actual people involved – Wilson’s surviving four sons (of five), plus their children, spouses and all the rest. The four women who Alec seduced, married and deceived – Gladys, Dorothy, Alison and Elizabeth – have all passed on. It is extremely moving. MI5, according to the closing captions, refuses to release the major’s file, which might allow the families to find some of the truth about his motivations – but his records are supposedly still too sensitive. Seems an unnecessary deception, 80 years on.