Una Kroll was eleven when she first met her father. They stopped for lunch on the way from Brighton to London and he took her outside to play with the innkeeper's Angora rabbit. In that pub garden this stranger uttered words that sent a chill through her heart, he would not be coming home. There was another woman. Scarcely comprehending, she buried her face in the white rabbit's fur and refused to cry. The lonely little girl already knew how to hide her tears and she had invented a childish fantasy about her absent father to fend off unsympathetic classmates. He was an aviator and explorer who had gone missing in the desert, she told them.

This was less extraordinary than the truth. Only years later did she discover that George Hill, her father, was a British spy who had befriended Trotsky at the time of the Russian Revolution. He had smuggled the Romanian crown jewels out of the Soviet Union and was involved in a doomed attempt to rescue the Tsar. During the Second World War he acted as the link between Churchill's Special Operations Executive and Stalin's secret service, the NKVD.

Una's mother, Hilda Pediani, had been one of his agents and one of many lovers. He married her so that Una would be legitimate, but took no part in the child's upbringing. It was a rare sympathetic act by a man who was capable of great bravery but little compassion.