The egg attack on King Charles and Queen Camilla underlines the security threat they face during public appearances, according to royal expert Richard Fitzsimmons.

He said: “What is so important to remember I think is that the walkabout has been a staple of royal life since 1970, when it began in the Antipodes.

“It causes such pleasure in the crowds, secondly, the royals can not only feel close to the people, but actually greet them. And it’s a nightmare, obviously, to the police.

“This happens so very, very quickly. It underlines the threat that’s always there when royals appear in public in exposed circumstances. But it is so pivotal and of course it’s so popular with the crowds and there have been so many famous images over the years.”

Speaking to Mark Longhurst on GB News, he said: “If you’re in charge of security, if you’re involved with security, then naturally you want things to be as secure as possible, and that would mean, as it were, being removed from the people which is the very last image that the royal family wants.

“It’s worth remembering, and I say this on the day when the Crown has been released, that the two most notorious security breaches were in 1974 when several people were injured during an attempted kidnapping by involving Princess Anne, and also in 1981 six blanks were fired the act the Queen during Trooping the Colour and she was completely unfazed.

“This is a sort of thing that is obviously a security nightmare. I would also add that neither episode, which showed the courage of the royals, appears in the Crown.”

Asked about the Crown, he said: “It’s a first class cast, the production values are excellent, but the royals are portrayed as being so nasty, so thoroughly disreputable, almost intolerably snobbish.

“Imelda Staunton’s got the Queen’s voice far better than Olivia Coleman…but the fact of the matter is that she is portrayed as heartless – the Queen had sensitivity and dignity.

“This series should have a disclaimer warning viewers that it is a fictional dramatisation of actual events.”

Asked if it is being broadcast too soon after the Queen’s death, he told GB News: “I think it’s unfortunate. I think it is a great mistake, frankly…some will believe what they see as true. A lot of it is rubbish.

“They should say that, they should at least go to the decency of putting a warning on screen that a lot of this is pure fiction, but I have to say it couldn’t have been more impressive.

“Of course, the 1990s when it’s set was a nightmare for the royal family but this is no way, in my view, to show it.”