Prince of Spies is a work of fiction, so any similarities between characters and circumstances in the book and real people should be regarded as purely coincidental.

That said, it is based on actual events and places in Europe during the Second World War. Some characters featured or referred to in the book did exist, Winston Churchill being an obvious example. Likewise, Air Marshal Harris was the actual head of RAF Bomber Command during the war.

Other less well-known examples include SS Obersturmbannführer Max Pauly (Chapter 20), who was the commandant of Neuengamme concentration camp and was executed as a war criminal in 1946. Just over 40,000 people were murdered at Neuengamme during the war.

Gruppenführer von Helldorf (Chapter 17) was the head of the police in Berlin during the relevant part of the story. He was executed by the Nazis in 1944 for his part in the bomb plot against Hitler.

Colonel General Friedrich Paulus (Chapter 19) was the commander of the German 6th Army, which suffered such a devastating defeat at Stalingrad. Hitler did indeed promote him to field marshal in a bid to prevent him surrendering, but Paulus did surrender and lived in East Germany until his death in 1957. The victory of the Red Army at Stalingrad in February 1943 was a key turning point of the Second World War.

Werner Best (Chapter 26) was the German Plenipotentiary (effectively the ruler) in Denmark from November 1942 until the country was liberated in May 1945. He was convicted as a war criminal but spared the death penalty. Best claimed he’d been involved in informing the Danish resistance about the planned deportation of the country’s Jewish population.

This deportation is referred to in the last chapter and is based very closely on real events. The Danish Jewish community and the resistance were tipped off about the planned deportations, and as a result, more than eight thousand Danish Jews and non-Jewish relations were smuggled across the Øresund to neutral Sweden. This was one of the very few examples of an occupied country resisting the maltreatment of its Jewish population.

Readers may possibly consider Agent Browning to be an unlikely figure working against his own government. In fact, there was a diplomat at the German Embassy in Copenhagen – Georg Ferdinand Duckwitz – who tipped off the Danish resistance about the planned deportations. There is no doubt that by 1943, Duckwitz was anti-Nazi, and he became a leading West German diplomat after the war.

The conference regarding the fate of Europe’s Jews (Chapter 26) is the Wannsee conference, which set in motion the Final Solution. The figures used in this context are accurate: some 2,700,000 Jews were murdered in 1942, mostly at the six Nazi death camps in Poland.

Like Agent Horatio (Otto Knudsen), there was a Danish businessman, Aage Carl Holger Andreasen, who picked up information about the V-1s and V-2s while travelling in Germany. He contacted the British, and after some doubt about his motives, he became a British agent.