In January 1943, a 22-year-old British officer gave a talk to entertain his men as the unit idled in the desert. The topic was “Occupied Europe”, with accounts of collaboration, resistance and murder in 15 countries, about which British newspapers said little. Yet Captain Frank Thompson, unit education officer and subject of A Very English Hero: the Making of Frank Thompson, by Peter J Conradi (Bloomsbury, £18.99) detailed the murder by the Nazis of 54,000 Jews at Babi Yar near Kiev, followed by the killing elsewhere of one million Jewish men, women and children by machine-gun, torture, hunger “and what Frank called ‘lethal chamber’”.

The talk was a tour de force. He held his audience enraptured for almost two hours as he passionately explained that the future of humanity was at stake in the coming struggle, that a Nazi victory would mean slave labour, starvation, torture and mass murder.

Frank’s information came largely from the Daily Worker; the Soviet War News; serving in an intelligence unit; and listening to Moscow Radio. But his passion came from the heart.

The handsome, Winchester-educated Thompson was a Communist Party sympathiser but too much of a rebel to obey party rules. He had instinctive sympathy for all downtrodden peoples and, as Peter Conradi explains in this magnificent and tragic biography: “that Frank at 22 understood that hatred entails loss of virtue is reason enough to honour and admire him.”

In addition, he was a fine poet and brilliant linguist proficient in nine languages. In April 1939, Frank had volunteered at the New Herrlingen School in Kent, founded by Anna Essinger, a German-Jewish refugee, for the many children arriving in England without parents, clothes or money.

Much of the book is about understanding what made this very English hero dedicate his life to fighting fascism. His parents came from a long line of missionary stock and much of his idealism can be traced directly to them. He joined the Special Operations Executive to avoid “the long littleness of life” and, in June 1944, aged 23, was captured, tortured and executed in Litakovo, Bulgaria, where today he is revered for his courageous fight for the country’s liberation.

Anne Sebba is the author of ‘That Woman: a Life of Wallis Simpson Duchess of Windsor’ (Phoenix £7.99)