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.
The Windsors' links with Germany remained a touchy subject however. There was embarrassment in the Eighties when Princess Michael of Kent's father, Baron Gunther von Reibnitz, was exposed as a former Nazi party member and SS officer.
Less well known is the fact that one of Prince Philip's sisters, Sophie, was married to Christopher of Hesse-Cassel, an SS colonel who named his eldest son Karl Adolf in Hitler's honour. Indeed, all four of Philip's sisters married high-ranking Germans.
The prospect of the former Nazis and Nazi sympathisers attending his wedding to the Queen meant he was allowed to invite only two guests.
As the Public Record Office releases more documents concerning the abdication of King Edward VIII, BBC News Online looks at his life.
King Edward VIII, who became the Duke of Windsor, found himself at the centre of a personal and political storm which shook the foundations of the monarchy.
More than 30 years after his death, his life continues to intrigue and tantalise historians.
Some commentators see him as a pampered playboy, whose louche lifestyle and numerous relationships with married women, most notably Mrs Simpson, made him unfit to be King.
Others believe this outward appearance masked something much darker - a fascination with Nazism, possibly even a brooding determination to overthrow his brother George VI.
The young Edward enjoyed a busy social life
Edward was born on 23 June 1894. His father, who became George V in 1910, was a fierce disciplinarian.
Besides Edward - always called David by his family - there were four other royal princes: Bertie - later George VI, Henry, George, and John.
Edward, good-looking, raffish and easy going, was the pick of the crop.
After becoming Prince of Wales in 1911 and serving in the Grenadier Guards during World War I, he became the darling of 1920s society.
Life was a seemingly endless round of balls, cocktail parties and country house weekends. His penchant for married women was already well-known in aristocratic circles.
During the early 1930s, Mrs Wallis Warfield Simpson, a divorcee from Baltimore, Maryland, was constantly with him.
But there was another, more serious, side to Edward's character.
During the Depression which followed the Wall Street Crash of 1929, he visited poverty-stricken areas of the UK and encouraged 200,000 unemployed men and women to join his back-to-work scheme.
His popularity far outstripped that of his distant father.
Following George V's death in January 1936, the new King faced two huge problems.
The first was his love for Wallis Simpson: as King, and Supreme Governor of the Church of England, he could not marry a divorcee. He would have to choose between his country and his lover.
The second was that some felt that the new King was too sympathetic to Nazi Germany.
Following Edward's accession, the German embassy in London sent a cable for the personal attention of Hitler himself.
In part, it read: "An alliance between Germany and Britain is for him (the King) an urgent necessity."
Alan Lascelles, Edward's private secretary, gave his own harsh judgment of the situation.
The Windsors met Hitler in 1937
"The best thing that could happen to him would be for him to break his neck."
Within the year Edward, pressurised by the Church of England, the government and royal courtiers, decided to abdicate.
In October 1937, Edward and his wife - by now the Duke and Duchess of Windsor - visited Nazi Germany.
They met Hitler, dined with his deputy, Rudolf Hess, and even visited a concentration camp.
The camp's guard towers were explained away as meat stores for the inmates.
At the outbreak of war, the duke served as a military liaison officer in Paris before eventually ending up in Lisbon after the French capitulation.
Hitler, wishing to bring the duke into his camp, made an abortive attempt to coax Edward and his wife to Spain, which was then sympathetic to the Nazi cause.
But the duke soon moved on to become Governor of the Bahamas from 1940-45. It was while he was there that he is said to have made his views explicit.
He reputedly told a journalist that "it would be a tragic thing for the world if Hitler was overthrown".
To an acquaintance on the island, the Duke reportedly said: "After the war is over and Hitler will crush the Americans...We'll take over...They (the British) don't want me as their King, but I'll be back as their leader."
After the war, the duke and duchess returned to France. He died there in 1972, while the Duchess lived on until 1986.
Though the official Whitehall view was that "His Royal Highness never wavered in his loyalty to the British cause", the reputation of "the King who never was" seems destined to remain cloaked in ambiguity.
Newly released FBI files suggest the alleged Nazi connections of Wallis Simpson prevented her marrying King Edward while he was monarch.
The revelations are contrary to the long-held belief that the stumbling block was the American's status as a divorcee.
King Edward abdicated the throne in December 1936, following a constitutional crisis, and married her in exile the following year.
These FBI files were written in the 1940s but are now released under America's Freedom of Information Act.
Wallis Simpson was viewed by some as an unsuitable wife
They suggest stronger connections between the Duchess of Windsor - as she was known after marriage - and the Germans than previously believed.
The documents are a combination of surveillance, informants and hearsay.
One memo said that the British Government, headed by Stanley Baldwin, had known for some time that the Duchess was exceedingly pro-German in her sympathies.
The FBI believed she was considered so obnoxious by the British that they refused to permit Edward to marry her.
Reports emerged last year that the FBI also sent agents to spy on the royal couple after allegations that the Duchess might have been passing secrets to a leading Nazi with whom she was thought to have had an affair.
It is suggested the surveillance had been ordered after President Roosevelt expressed concern about the couple's politics.