Rival law-enforcement agencies arguing about which of them should investigate a murder has, of course, been a staple of crime dramas for decades. Rather less common, though, is for the agencies in question to be the Metropolitan Police, the Gestapo and the SS.

SS-GB (BBC1, Sunday), based on Len Deighton’s novel, poses the undeniably interesting question of what this country would have been like in 1941 if Germany had won the Battle of Britain.