Linked by blood but twice divided by war, the royal family's relationship with Germany, its people and its troubled history has long been a sensitive one. The photograph of Prince Harry wearing a swastika has echoes of one particularly disturbing incident involving the family, one which seared itself into the British collective memory - that of the Duke and Duchess of Windsor meeting Adolf Hitler in 1937.
The ex-King Edward VIII and his wife were known sympathisers of the Nazis and their policies, a feeling shared by a large number of British aristocrats who admired the way Hitler was dealing with the Communists.
The Nazis regarded the duke, who had abdicated over his affair with divorced American Wallis Simpson, as a potential ally and a possible head of state for a subjugated Britain.
But his flirting with Hitler's regime threatened to undermine years of work by the royal family to distance themselves from their German roots.
The modern royal family was founded in 1840 when Queen Victoria married Albert of Saxe-Coburg, a Germany duchy, creating The House of Saxe-Coburg-Gotha. Such was the ill-feeling towards all things German during the First World War that in 1917 Victoria's grandson King George V - an honorary Field Marshal in the German army - thought it prudent to renounce the German name and titles and adopt that of Windsor.
It was a masterful PR exercise, replacing the Teutonic surname with that of a quintessentially home counties town.
His son Edward VIII once declared: "There is not one drop of blood in my veins that is not German." Both he and George VI were bilingual in German and English.
Throughout the Twenties and Thirties, the royals were steadfastly opposed to conflict with their ancestral fatherland. Indeed George V's wife Queen Mary always maintained that Britain had "backed the wrong horse" in 1914.
His son's meeting with Hitler threatened irrevocably to undermine the royal family's support among their subjects.
It took the Queen Mother's steadfastness in the face of German bombs and her visit to the East End during the Blitz to restore public faith in the family.