Bill Ash is a genuine Boy’s Own hero of whom you have probably never heard. But because Patrick Bishop writes like a dream, you are unlikely ever to forget him. Born in Texas, Ash was appalled by the rise of Nazi Germany. Long before the US entered the war, he renounced his American citizenship, travelled north to join the Royal Canadian Air Force, went to Britain and transferred to the RAF. By the time he was twenty-five he had been shot down (crash-landing in France), captured, interrogated and, in 1942, sent to Stalag Luft III, a German prison camp solely for RAF captives ninety miles southeast of Berlin. The Germans usually treated them well because they regarded the British as their social and cultural equals, unlike their Russian and Jewish captives, few of whom survived the war.

Inside the camp, Ash devoted himself to constant, inventive and dangerous tunnelling, though he never managed to escape for more than a few days. After being recaptured, he usually spent many weeks in the solitary confinement block (‘the cooler’). One nearly successful escape, under the latrines, was especially clever, if