Prince George turned 12 on July 22 – an important milestone for the future king in more ways than one.

Richard Eden, the Daily Mail’s Diary Editor and a previous royal helicopter pilot, mentioned: ‘When Prince William turned 12, he ceased traveling with his father, resulting in separate flights for them. This was clearly to secure the line of succession.

‘It will be fascinating to observe if this practice continues with George and William, given that we know they have traveled together by plane, helicopter, or car.’

But this is when Rebecca English, the Daily Mail’s Royal Editor, who has been covering the royal beat since 2004, interjected.

‘I spoke to the Palace this week,’ she said, ‘and they were like “Well, it’s kind of news to us.”

‘I get the impression that the family won’t be changing their travel arrangements at all.’

Jo Elvin, who hosts the hit YouTube show as well as making regular appearances on ITV’s Lorraine, was puzzled by the Palace’s response.

Richard Eden, the Daily Mail’s Diary Editor, said it was ‘worrying’ the royal protocol would not be followed

Richard Eden stars on the hit YouTube show alongside the Daily Mail’s Royal Editor Rebecca English (centre) and host Jo Elvin (right)

Prince William and Prince George watch the Wimbledon Tennis Championships on July 13

‘I remember being a kid and my father telling me about that as a bit of royal protocol,’ she said. ‘It’s weird.’

‘Yeah,’ Richard said. ‘They don’t like talking about security and talking about travel arrangements.

‘But I have to say, I mean, it’s not a very tasteful discussion, but it is the future of our royal family and I personally find it very worrying.

‘Look, after the Wales Family, we have Harry and Meghan!’ he exclaimed.

‘Although it sounds implausible, there were whispers that Meghan allegedly remarked, “we’re only one plane crash away from being on the throne.”

‘I am sure she didn’t as it’s a very tasteless comment but the fact is, Prince Harry and Meghan could be on the throne and that is something, I would say, would be a threat to the future of the monarchy.’

Pleading to the Wales Family, he said: ‘Come on, even though it’s not great for the environment, please put George on a separate flight and a separate helicopter from his father.’

‘My understanding is that he would still be able to travel with his mother,’ Jo added.

Rebecca English, who has covered the royal beat since 2004, said she got the impression the Wales Family ‘won’t be changing their travel arrangements at all’

Prince George at the coronation of King Charles III. As the prince turns 12 he now faces a major change in royal protocol

George with his mother and two siblings, Louis and Charlotte, during the celebrations for the 80th anniversary of VE day

To which Rebecca replied: ‘Yeah, but as I say, I don’t think the family will change their travel plans at all.’

This does not seem to align with the wishes of King Charles and the late Queen Elizabeth II – both of whom expressed their concerns about the Wales Family flying together.

‘Not only do they travel together,’ Richard explained, ‘Prince William, who is a qualified helicopter pilot, actually flies the helicopter.

‘According to Robert Jobson’s book, the King didn’t like William flying the whole family and urged him to stop.

‘It is something that Queen Elizabeth expressed her concerns about as well. I think she was always keen to make sure that she did travel separately from the heir-to-the-throne Charles.

‘It is a matter of some importance, I would say,’ he added.

Speaking exclusively to MailOnline, royal expert Richard Fitzwilliams added important historical context as to why this rule was followed so ardently by the late Queen.

The experienced royal commentator told MailOnline that the bizarre rule was established following a string of tragic deaths in the family involving aircrafts.

Prince William and Kate Middleton disembark a plane with George and Charlotte during a trip to Canada in 2016. From his  12th birthday, George will no longer be permitted to fly on the same plane as William

A young Prince George and Princess Charlotte during a visit to Poland in 2017. As per royal protocol, girls in the family must wear dresses and the boys must wear shorts 

The Prince and Princess of Wales alongside a baby George disembark a plane in Australia in 2014. From George’s 12th birthday he will need special permission to fly on the same plane as William 

‘The unexpected can happen, as with Prince William of Gloucester’s tragic death in 1972, though this was in a competition,’ Richard said.

‘Prince George, Duke of Kent also died in a plane crash in 1942, which has become controversial. 

‘Prince Philip’s sister, Cecile, died in a plane crash in 1937, giving birth to a stillborn child,’ he added. 

These tragedies have only served to reinforce the Royal Family’s belief in ensuring the heirs travel separately. 

Richard noted that a similar policy exists across the pond where the President never travels by plane with the Vice-President. 

Whilst this new royal protocol may be one that the Wales Family choose not to follow, it is just one of many rules George and his siblings are subject to.

These include always travelling with a change of black clothes should a member of the family die unexpectedly. 

This rule was introduced after King George VI died while Elizabeth was in Kenya and she did not have any black clothes.

George joins his father at an event in Buckingham Palace meeting World War Two veterans.  

The children also face limits on what they can and can’t wear with the girls expected to wear dresses and the boys must wear shorts.

On top of this, they can never eat shellfish while on a royal tour to avoid food poisoning.

For more fascinating insights from the Mail’s team of unrivalled experts, watch the latest episode of Palace Confidential in full now, subscribe to the Daily Mail Royals YouTube channel and sign up to the FREE Palace Confidential newsletter.