Prince George will now be forced to be separated from Prince William and Princess Charlotte

From this day forwards, a long-standing royal tradition will come into play which could see Prince George separated from his family.

More specifically, it's his parents Prince William and Kate Middleton as well as younger sister Princess Charlotte that the future king will be distanced from going forward.

But in what way? And why today (22 July) specifically?

Well, as many royal family fanatics will know, today marks the 12th birthday of little Prince George - and if tradition is to tell us anything, this milestone marks the commencement of official preparations for the throne.

This isn't to say that we're expecting the youngster to be crowned anytime soon, with both grandfather King Charles III, 76, and father William, 43, likely to have long reigns ahead of them.

George celebrates his 12th birthday today (Chris Jackson/Getty Images)

The issue is, however, that future monarchs can never be totally certain when they'll have to step up to the powerful plate.

Look at George's late great-grandmother, Queen Elizabeth II. She was forced to takeover the institution aged just 25 following the premature passing of her father, George VI in 1952.

Years earlier, George himself was forced to take over from his brother, the former King Edward VIII, who abdicated the throne to marry American actress Wallis Simpson in 1936, which was rather the scandal at the time.

As such, preparation must be put into place to ensure the future of the monarchy, which includes keeping William, George, and - until the latter has children of his own in the coming years - Charlotte, safe.

As such, the likely group won't be permitted to travel together in the future, as two members in succession must be kept apart in case of worst case scenarios.

William was also separated from his family from his 12th birthday (Tim Graham Photo Library via Getty Images)

This includes plane crashes, which killed Prince Philip's sister Princess Cecilie in 1937, Queen Elizabeth II's uncle Prince George in 1932, and the late Queen's cousin, Prince William of Gloucester, in 1972.

William had to endure the same tradition from his 12th birthday, and wasn't allowed to fly with father, Charles, or little brother Prince Harry again.

"We flew all four: the Prince, the Princess, Prince William and Prince Harry, up until Prince William was 12 years old," King Charles' former pilot, Graham Laurie explained to OK! last year.

"After that, he had to have a separate aircraft and we could only fly all four together when they were young with the written permission of Her Majesty.

"When William became 12, he would fly normally in a 125 from Northolt and we would fly the 146 out with the other three on."

The separation tradition is unwritten and largely undocumented, however, and apparently, if William and George did want to continue flying together, it could be possible, but only with the reigning monarch's position.