Britain 1952 and the nation should be enjoying the fruits of the end of post-war austerity and a new Elizabethan age.

But history has taken a horrendous wrong turn in C.J. Sansom’s all too plausible novel. For this is a world in which the appeaser Lord Halifax became Prime Minister instead of Winston Churchill in 1940. Instead of “fighting in the fields and in the streets”, Halifax and his Cabinet opted to sue for peace with the Nazis in the face of apparently certain defeat after Dunkirk. Hitler’s terms seem generous. As in 1938, the people are delighted as full blown war seems to have again been averted. Only over time, does the true cost of British capitulation become clear.

By 1952, Britain is emotionally and physically drained by the strain of Nazi domination and a seemingly endless war with the Soviet Union. The government is an unholy coalition of…