Prince William has taken offence to his brother refusing to call Princess Kate by her preferred name.

Prince William is “furious” with Prince Harry and Meghan Markle because the pair “deliberately” refer to his wife as Kate instead of Catherine.

The Princess of Wales reportedly asked her friends to refer to her as Catherine instead of Kate just before she married into the Royal Family, because it is the name she prefers.

However, the Prince of Wales has reportedly taken offence to the Duke and Duchess of Sussex publicly referring to his wife as Kate “even when they were sending her get-well-soon messages after her cancer diagnosis”, according to a friend of the couple.

A friend of William and Catherine told The Daily Beast: “William takes offence at people calling Catherine ‘Kate’, because she has asked to be known as Catherine.

“It’s a fairly simple wish to respect. I’m sure Meghan wouldn’t like it if William started publicly calling her ‘Meghan Markle’.

“Of course it’s an utterly trivial thing, but those of us who know William know that it is one of the things that pushes his buttons. Pushing his buttons while he was going through his wife’s cancer seemed an entirely unnecessary and deliberate irritation.”

Another friend of the couple added that it was “bloody rude” of Harry and Meghan to call the Princess of Wales Kate.

“No one’s saying it’s responsible for all the trouble, but deliberately calling someone by a name they don’t like is just bloody rude,” said the friend.

“If Harry and Meghan were serious about healing their issue, a good first step would be to call her Catherine.”

The apparent reluctance on Harry and Meghan’s part to call the Princess of Wales by her preferred name was “an entirely unnecessary and deliberate irritation” and may have contributed to William and Kate’s refusal to respond to Harry and Meghan’s expressions of sympathy after her cancer diagnosis.

The name request sent by Kate came in 2008 – two years before William ultimately popped the question.

Prince Harry also previously wrote in his bombshell memoir Spare that the now-King “asked his daughter-in-law to change the spelling of her first name”.

The former working royal claimed that his father wanted his sister-in-law to change her name spelling from a C to a K.

The Duke of Sussex wrote that he spoke to his brother at the time about their father’s suggestion: “I turned to Willy, gave him a look that said: ‘You listening to this?’ His face was blank.”

Kensington Palace has been approached for comment.