Charles and Camilla wanted Catherine to spell her name with a K, claims Harry

Charles and Camilla wanted the Princess of Wales to spell her first name Catherine with a K, Prince Harry has claimed in a leaked extract from his memoir.

Catherine, who was widely known as Kate Middleton before she married Prince William, was urged to to change the spelling because as were 'too many' people in the family who started their name with the letter ‘C’, according to the Duke of Sussex.

Harry claimed the King and Queen Consort Camilla wanted the Princess to spell her name Katherine when she became a member of Royal Family.

The lettering, it was claimed, would be more confusing when cyphers, or personal monograms of a Royal Family members were used if Charles, Camilla and Catherine all used ‘C’.

The spelling of Catherine Middleton's name could cause 'confusion' it has been claimed (Getty Images)

Prince Harry also says how much Charles liked his sister-in-law’s hair and had "often spoken" about the Princess' long brunette locks, reports the Daily Mail.

Charles and the late Queen, the book says, liked "women with their hair down" and who wore minimal make-up.

Prince Harry says Meghan emulated the flowing long hair look when she first met her future father and mother-in-law at Clarence House (Getty Images)

He says Meghan emulated this look when she first met her future father and mother-in-law at Clarence House and ate crumpets along with marmite and salmon sandwiches.

Prince Harry's memoir Spare is due to be published on Tuesday but early copies have gone on sale in Spain with an English-language edition also leaked ahead of the official publication date.

Prince Harry also says how much Charles liked his sister-in-law’s hair (Getty Images)

Charles and the late Queen, the book says, liked 'women with their hair down' and who wore minimal make-up (Getty Images)

The Duke of Sussex's autobiography has delivered a number of bombshell claims about the royal family, from an allegation of Prince William physically assaulting him to the brothers asking Charles not to marry Camilla.

But a source in the US claimed the revelations almost never came to light.

After Harry and Meghan attended the Queen's Platinum Jubilee in June, the team working on Spare were reportedly told: “He’s pulled it. He doesn’t want to do it.”

The duke is thought to have received a multi-million pound advance for the book but a report in the Times says insiders at publisher Penguin Random House speculated that Harry was told that if the book were published while the Queen was alive, there would be “no way back”.