Prince William was given the title — the highest rank in British peerage — by his grandmother, the Queen.
Commoner Kate Middleton will now become Her Royal Highness the Duchess of Cambridge when she marries the Prince in Westminster Abbey.
William, 28, will also become the Earl of Strathearn and Baron Carrickfergus, which means Kate will become the Countess of Strathearn and Baroness Carrickfergus.
All titles are a gift from the Queen and it was up to the monarch to choose which one to bestow on her grandson and his new wife.
But William’s thoughts will also have been taken into account by the Royal matriarch in a private discussion between the Prince and his grandmother.
Tradition dictates that Royal men receive a title on their wedding — and often more than one.
Buckingham Palace said in a statement: “The Queen has today been pleased to confer a Dukedom on Prince William of Wales.
“His titles will be Duke of Cambridge, Earl of Strathearn and Baron Carrickfergus.
“Prince William thus becomes His Royal Highness The Duke of Cambridge and Miss Catherine Middleton on marriage will become Her Royal Highness The Duchess of Cambridge.”
As well as a duchess, Kate, 29, is also technically Princess William of Wales.
According to protocol, she is not officially Princess Catherine as she was not born a princess in her own right.
Instead she adopts her husband’s first name, in the same way as Princess Michael of Kent, who married the Queen’s cousin Prince Michael of Kent.
But it is likely that in the eyes of the media and public, she could always be known as Princess Catherine or Princess Kate.
The Duke of Cambridge was seen as the favourite for William’s new title in the run-up to the wedding.
The Queen even paid a visit to the city just two days ago.
Charles Kidd, editor of Debrett’s Peerage, said of the dukedom: “It’s a well-known place and I think it will have some resonance with the public.”
The last Duke of Cambridge was a famous military figure who wed a commoner for love but then also kept a mistress for more than 30 years.
Born in 1819, Prince George, a grandson of George III, married actress Sarah Louisa Fairbrother in 1847 when she was pregnant with their third child but his marriage was never recognised by his cousin Queen Victoria.
Like William, this Duke of Cambridge joined the Army. He served in the Crimean War and was promoted to commander-in-chief in 1887.
Once married, the newlyweds will pass a statue of the Duke sat on a horse close to the Ministry of Defence in Whitehall in their carriage procession.
The last Duchess of Cambridge was the glamorous German-born Princess Augusta Wilhelmina Louisa of Hesse-Cassel, married to Prince Adolphus Frederick, the 1st Duke of Cambridge and mother to Prince George, the 2nd Duke of Cambridge. (*)
SOURCE : THE SUN.CO.UK