All four of Philip’s sisters married German princes – family unions which proved uncomfortable during wartime hostilities with Britain.
The husbands of three of them – princesses Margarita, Theodora and Sophie – served as German officers during the Second World War, while Philip and his uncle “Dickie” Mountbatten were on the Allies’ side, fighting for the Royal Navy.
Sophie’s first husband, Christoph, Prince of Hesse, was involved with the Nazi Party and flew with the Luftwaffe.
Despite his Nazi connections, he was said to have become disillusioned with Adolf Hitler by 1942.
He joined the Luftwaffe as a navigator at the beginning of the Second World War and flew bombing missions over Holland, France and Russia, but his family maintained that he never bombed Britain.
The prince was killed when his aircraft crashed in fog in 1943.
Sophie remarried and her second husband was also a German prince, George William, Prince of Hanover.
She was the last of the duke’s sisters to pass away, dying in 2001 at the age of 87.
Margarita, Philip’s eldest sister, married Gottfried, Prince of Hohenlohe-Langenburg.
She died in Bavaria in April 1981.
Theodora married Berthold, Margrave of Baden, and lived at Schloss Salem, near Lake Constance, in Germany, a residence beating Buckingham Palace for size if not treasure.
She died at Constance in October 1969.
Philip’s other sister, Cecile, who married George, Prince of Hesse, was tragically killed in a plane crash.
Cecile, her husband, two of their children and Cecile’s unborn baby died in 1937 while on their way to London for a family wedding.
Their aircraft collided with a chimney stack in fog near Ostend in Belgium.
Philip was 16 at time.
In light of their German connections, none of the duke’s remaining sisters was invited to his wedding, which took place in 1947 just two years after the end of the Second World War.