The Duke of Edinburgh title had previously been held by the King and Prince Edward’s father Prince Philip for more than 70 years. While Prince Edward and Duchess Sophie are senior working royals, their two children Louise and James are unlikely to do the same, and currently do not use HRH titles.

The Duke and Duchess of Edinburgh once had to sleep in an unexpected location when staying at Sandringham House in Norfolk.

Specifically, William hopes to tap Prince Edward and Duchess Sophie's two kids, Lady Louise Windsor, 21, and James, Earl of Wessex, 17.

Much like Princess Kate, Duchess Sophie was a normal citizen prior to marrying into the Royal Family. In fact, Sophie, the Duchess of Edinburgh, had a successful career before she married Prince Edward. As a result, Sophie had to "reduce her expectations" in many respects after marriage.