Biographies of the little-known generally attract no more attention than their subjects did in their lifetimes – unless, as with Claire Tomalin’s excellent biography of Dickens’s mistress Nelly Ternan, they are associated with more famous figures. I knew that Alan Hillgarth was an influential Second World War naval attaché at the British embassy in Madrid, but that was all. He bore a torch in that great conflagration, like many thousands of others, but you need to be painted in big, bold colours to show up in the crowded pages of history.

Or perhaps you need a biographer such as Duff Hart-Davis. Drawing on family sources, thousands of letters and official records, he has created not just a fascinating and significant life but also a portrait of a time and a culture that is rapidly passing from living memory.

Hillgarth was born in