THE myth of the British monarchy has been "shattered" following the latest revelations from Prince Harry in his new book, a republican campaign group has claimed.

Republic has said any sense of the institution's "magic" has now evaporated after Harry claimed his brother William physically assaulted him after he attempted to stand up for his wife Meghan Markle.

Graham Smith, a spokesman for the group, insisted the royal family now look like very "ordinary and unimpressive people" and Charles and William are "not men we would elect as head of state".

He said Harry's claims cannot simply be dismissed as a "family feud" and will spark a renewed opposition to the monarchy.

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Smith said: "Whatever you think of the revelations in Harry's book, this row is destroying the monarchy and any sense of mystery or mythology that has sustained it in the past.

"We can now see very ordinary, unimpressive people who are prone to quick tempers, fits of violence, and petty jealousies."

"The kind of behaviour demonstrated by William has been talked about for years, now Harry is throwing a spotlight on it and it can no longer be ignored.

"Charles and William are not men we would elect as head of state, if we were given the chance, yet there they are.

"We have people at the top of our society most of us would actively vote against in a free and fair election, because the King and heir would not withstand the scrutiny and challenges that comes with that contest.

"We cannot dismiss the allegations as a family feud when the family is the basis for a hereditary monarchy. The serious problems within the royal household destroy a significant part of the justification for the institution.

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"Harry has also highlighted the cruelty of an institution that raises children according to a rigid pecking order, telling the younger ones they must always defer to the rights and rank of their siblings.

"This is no way to raise a family, it is no way to govern a country. The British people will see that, and will increasingly know it is time the monarchy went."

Harry's memoir, entitled Spare, is due to be published on January 10 and has been seen by the Guardian which has reported on some of its key revelations.

It details one confrontation between Harry and William in 2019 at Nottingham Cottage in the grounds of Kensington Palace – where the younger brother was then living.

Harry claims that William called Meghan “difficult”, “rude” and “abrasive” – which led him to accuse his brother of parroting the British tabloids' narrative about her.

Harry said William was “piping hot” when he had arrived at the cottage, and after a verbal exchange he had told his older brother: “Willy, I can’t speak to you when you’re like this.”

"He grabbed me by the collar, ripping my necklace, and he knocked me to the floor," Harry said.