Father and wife's illnesses focus attention on future king, William

With both his father King Charles and his wife Kate absent from public duties as they undergo treatment for cancer, Britain's Prince William has come under the media and public spotlight like never before.

As heir to the throne and as a son of the late Princess Diana, the 41-year-old is accustomed to the scrutiny that comes with being a British royal.

But his father and wife's absence from public life since mid-January have meant even greater attention has turned to the future King William V.

From the moment his grandmother, the late Queen Elizabeth, died in September 2022, he would have been all too aware of the "scary" reality of his destiny, said Anna Whitelock, history of the monarchy professor at London's City University.

"He knows he has to be ready to be king," she told Reuters.

"When (the king's) cancer diagnosis came, of course, I'm sure his first reaction was as a son, concern for his father. But there is also this big weight of responsibility that suddenly starts to kind of descend upon his shoulders. And I'm sure he's very, very aware of that."

William was at the centre of some golden years for the royal family in the last decade with public celebrations and outpourings of support at his and Kate's wedding in 2011, the births of their three children, and milestones in the reign of his grandmother Elizabeth.

But the last few years also saw a high-profile fallout with Prince Harry, his younger brother's exit from royal duties along with wife Meghan, and their criticism of the institution. There was also the scandal over his uncle Prince Andrew's friendship with the late sex offender Jeffrey Epstein.

The death of Elizabeth and of her husband Philip the year before left the monarchy looking noticeably smaller, something brought into sharp relief by the current absence of Charles, 75, and Kate.

"He must be absolutely devastated and worried about his wife, about his children and about his father, on top of all the problems he's had with his brother," royal biographer Claudia Joseph said.

"I think it's very tough. But .. he's made of stern stuff. He's very stoic."

WILLIAM WILL 'STEP UP'

"That's the challenge for me is how do I make the royal family relevant in the next 20 years' time, and it could be 40 years' time, it could be 60 years' time and I have no idea when that's going to be. I hope that's something that I can do."