Queen Elizabeth will hand over some of her most important duties to her son Prince Charles because of her advancing age.
The 87-year-old monarch yesterday announced she will not attend the Commonwealth Heads of Government (CHOGM) meeting in Sir Lanka in November, the first time she has missed the biennial event since 1973.
Charles, 64, will attend in his mother's place.
"I can confirm that the Queen will be represented by the Prince of Wales," a Buckingham Palace spokesman said.
"The reason is that we are reviewing the amount of long-haul travel that is taken by the Queen. As a result of that she won't be travelling to the CHOGM later this year."
It is the first significant duty the Queen has passed on to her son, leading many to speculate this is the beginning of Charles' ascent to the throne.
He will also attend the State Opening of Parliament tomorrow, for the first time since 1996.
The Queen is believed to have made the decision to effectively "job-share" with Charles in light of her recent hospitalisation for gastroenteritis.
Although the Queen is very healthy for her age, her staff is gradually reducing her workload to ensure it doesn't become an unmanageable burden in years to come.
The decision to reduce the number of long-haul flights she takes puts any future trips to Australia in doubt.
The last time Her Majesty travelled Down Under was in 2011 for the last CHOGM.