Prince William, it is often said, has come a long way.

The ‘Party Prince’ of yesteryear has today been replaced by a loving father who rarely fails to cut a dignified and often humorous figure in public.

At 41, the Prince of Wales is not only a key force in the monarchy but popular with the public, too.

The outlook has not always been so sunny, though, as author Robert Lacey explains in his best-selling biography, Battle of Brothers. Storms were all too frequent.

William looks a less than happy as he follows his father in Glasgow

The brothers are together at Westminster Abbey in March 2020. It is the last official enagement for Harry and Meghan –  and the mood is sombre

William, head bowed down, stands with Prince Charles outside Clarence House as the celebrate the Queen Mother’s 98th birthday

Perhaps that is to have been expected. King Charles himself has been no stranger to the occasional outburst.

Nonetheless, William’s step-mother Camilla was said to have been taken aback by the ferocity of his tantrums.

‘He has proved no Sweet William when roused,’ writes Lacey.

‘In the years after her 2005 marriage to Prince Charles, Camilla recounted to members of her own family and close friends her surprise at discovering this unexpected side to Prince Charming – “the boy’s got a temper!”

‘Charles’s wife was horrified at the ranting and raving that William unleashed on occasion against her husband in her presence.

‘The rows were shattering, by Camilla’s account in the early days, with William doing the shouting and Charles submitting meekly on the receiving end. As she described it, William held nothing back.’

It was a wrath, suggests Lacey, commensurate with William’s sense of himself as future King.

Today, it is largely hidden, but younger brother Harry has his own views on William’s anger.

Writing in his memoir, Spare, Harry claims that in one 2019 row at Nottingham Cottage in the grounds of Kensington Palace, William had ‘grabbed me by the collar, ripping my necklace, and he knocked me to the floor.’

A dog bowl was apparently broken in the fracas. (Prince William has never given his version of events.)

According to Lacey, the anger had been apparent from early on, notably when his mother, Diana, had appeared in a 1995 Panorama interview with the now disgraced Martin Bashir.

To the profound embarrassment of William, then studying at Eton College, his mother had appeared on national television discussing the breakdown of her marriage to his father and her affair with James Hewitt.

According to a friend, the ‘healer’ Simone Simmons, Diana soon felt the full force.

‘’’All hell broke loose,” Diana told Simmons. ‘…He started shouting and crying and when she tried to put her arms around him, he shoved her away.

‘Diana was getting a taste of how William’s intensity could lead to his notorious rages. The following day, he apologised to his mother for his temper with a small bunch of flowers.’

Princess Diana felt the full force of William’s temper after the Panorama interview in 1995

Robert Lacey says that Prince William used to rant and rave against his father

‘The rows were shattering,’ by Camilla’s account to friends

Camilla was said to have been taken aback by the ferocity of William’s tantrums

Writing in the Daily Mail, Lacey concluded:

‘It should be stressed that in recent times — and particularly since the adjustments that the Royal Family had to make in 2019 and 2020 in the wake of their disagreements and the departure of Harry — father and elder son have grown much closer together.

‘Prince Charles and Prince William now clearly appreciate the need to work closely together for the future of the monarchy.’