When Philip turned twelve it was time to move from Cheam. He might have been expected to enter one of the great fee-paying schools in England, but the German side of his family intervened. His sister Theodora had married Berthold, the Margrave of Baden, in 1931. Her father-in-law Prince Max of Baden, the last Imperial Chancellor of Germany, had founded Salem School with the help of his personal secretary, Dr Kurt Hahn, in 1920 in his family home in Germany. By 1933, when Philip arrived, there were 420 pupils, and Salem was considered one of the finest schools in Europe. The curriculum was rigorous, being based on physical fitness and self-reliance, and Theodora succeeded in persuading the Milford Havens that Philip should go to Salem.

But the timing could not have been worse. In January of that year, Hitler had come to power as chancellor, and the Nazis quickly established control over every aspect of life there. Soon Kurt Hahn, a Jew, was in trouble with the authorities. The Nazis could not allow a Jew to educate the youth of Germany, so he was arrested and imprisoned. Influential people from all over Europe, including British Prime Minister Ramsay MacDonald, petitioned Hitler to set Hahn free. As a result, he was allowed to emigrate to Britain where he set about establishing a new school in Scotland – Gordonstoun.

Philip lasted less than a year at Salem. He got into trouble for mocking the Nazi salute and when the Hitler Youth began to infiltrate the school, Theodora agreed he should return to England and Gordonstoun. The school was in its infancy when Philip arrived in the autumn term of 1934. There were only twenty-six pupils, but such were Hahn’s abilities that the numbers grew to 156 by the time Philip left in 1939.

Hahn took an immediate liking to Philip. ‘When Philip came to the school,’ he wrote, ‘his most marked trait was his undefeatable spirit . . . his laughter was heard everywhere . . . In his schoolwork he showed a lively intelligence. In community life, once he had made a task his own, he showed meticulous attention to detail and pride of workmanship which was never content with mediocre results.’