Prince Charles has been approved as the successor to Queen Elizabeth as head of the Commonwealth at a meeting of the group's heads of government in Windsor, Sky News has reported.

The decision comes after the 53 leaders from Commonwealth nations, including New Zealand Prime Minister Jacinda Ardern, met at Windsor for a retreat to discuss the issue as part of the Commonwealth Heads of Government meeting in London this week.

While Queen Elizabeth has been head of the Commonwealth since 1952 the role does not necessarily go to the British monarch and is up to the members to decide.

There had been calls for the role to be rotated around the 53 member-states, most of which are former British territories.

But in recent days the Queen, the British government and other leaders have backed Charles to take on the role.

On Thursday, the Queen said it was her "sincere wish" for her son to carry on her work as leader of the Commonwealth.

The Queen will turn 92 on Saturday and it's likely this is her last CHOGM meeting given that the next one is held in Malaysia and she no longer does long-distance travel.

Speaking at the opening of the CHOGM meeting in London on Thursday, her Majesty said she never could have guessed that in 1952 when she became leader of what was then eight nations, it would later comprise 53 and 2.4 billion people.

"It is my sincere wish that the Commonwealth will continue to offer stability and continuity for future generations, and will decide that one day The Prince of Wales should carry on the important work started by my father in 1949," she said.

"By continuing to treasure and reinvigorate our associations and activities, I believe we will secure a safer, more prosperous and sustainable world for those who follow us: a world where the Commonwealth's generosity of spirit can bring its gentle touch of healing and hope to all."

That evening, Prime Minister Malcolm Turnbull — sitting next to Canadian PM Justin Trudeau — joined other world leaders who rubbed shoulders with the Royal family during a leader's dinner at Buckingham Palace.

The Queen said she was happy to welcome leaders into her home in the first CHOGM held in London since 1997.

"Here at Buckingham Palace in 1949, my father met the Heads of Government when they ratified the London Declaration, which created the Commonwealth as we know it today — then comprising just eight nations," she said.

"It is my sincere wish that the Commonwealth will continue to offer stability and continuity for future generations, and will decide that one day the Prince of Wales should carry on the important work started by my father in 1949.

"By continuing to treasure and reinvigorate our associations and activities, I believe we will secure a safer, more prosperous and sustainable world for those who follow us: a world where the Commonwealth's generosity of spirit can bring its gentle touch of healing and hope to all."

Prince Charles also made a tacit pitch for the role, saying the Commonwealth had been a "fundamental feature" of his life since first visiting Malta at age five.