Five years ago – before cancer, before Oprah, before becoming King – the then Prince Charles spoke of his hopes of being a “peacemaker”.

“I have spent much of my life trying to bring people together,” he said. “I try.”

King Charles hosts Ukrainian President Volodymyr Zelensky at the Sandringham Estate.Credit: Getty

After an extraordinary row at the White House, now, finally, is his chance to broker peace on a global scale and, in doing so, cement his legacy as King Charles III.

The King, whether he entirely chose to be or not, now finds himself at the centre of a triangle that seems to hold the fate of the Western world in its hands: Donald Trump, Volodymyr Zelensky and Sir Keir Starmer.

Trump counts the King as a friend. Charles has been a vocal supporter of Ukraine, meeting Zelensky and his wife twice before. Starmer, his third prime minister, sees him at least weekly for counsel.

US President Donald Trump (right) hosts UK Prime Minister Keir Starmer at the White House, holding a letter from King Charles III inviting him to make a state visit to Britain.Credit: nna\riwood

With the two presidents smarting from a “showdown” at the White House that horrified Europe and left Russian state media cheering, Starmer must now walk a diplomatic tightrope he could not have prepared for.

A mediator is needed, and fast.

The King, who is still undergoing cancer treatment, finds himself in the frame.

It was only three days ago that Starmer presented a personal letter from the King to Trump, handing it over with great flourish at the........

© The Sydney Morning Herald