Prince William has "a notably short fuse" in private and can sometimes be difficult to handle, a royal author has claimed.
Journalist Robert Jobson writes that the Duke of Cambridge "can be a bit of a shouter" and his "temper can "blow up at any time" when the future king is frustrated or when an issue concerns his family.
Mr Jobson, writing in the Mail as William prepares to mark his 40th birthday, quotes royal sources who described the prince as an emotional character who, along with his brother Harry, has occasionally unpredictable "extreme mood swings" - as did their mum, Diana.
A former courtier reportedly told Mr Jobson: "They both have quite extreme mood swings, just as Diana did. She could be your best friend one minute and the next your worst enemy."
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Mr Jobson claims the Princes' father, Prince Charles, has admitted he finds it difficult to measure his sons' sometimes unpredictable moods.
Insiders reportedly claim even William's senior aides will "check which way the wind is blowing" before asserting themselves around him or broaching subjects that may be problematic.
Another close aide reportedly told Mr Jobson that William and wife Kate are known to have passionate discussions every now and then.
They said: "He can be a bit of a shouter when he loses it. It’s fair to say the Duke and the Duchess give as good as they get if their disagreement results in raised voices.
"But they know each other so well, it usually blows over quickly – and she is, on the whole, a major calming influence on him."
The couple has been married for almost 11 years.
They have known each other since they were at university together and William reportedly had no shortage of attention from girls.
And when he settled down with Kate, many thought she was one very lucky lady.
But when one of the now-Duchess's friends put this point to her, she reportedly had a brilliant response.
During their university days at St Andrews, a friend told Kate how lucky she was to be going out with William.
And according to Claudia Joseph, author of Kate Middleton: Princess in Waiting, Smiling, Kate simply replied: "He's lucky to have me."
Although Kate wasn't born into royalty, she was born into an upper-middle class family, with her father being the son of a wealthy Yorkshire family with ties to the British aristocracy.
