William postponed all his planned engagements to look after his three children after Kate, 42, underwent planned abdominal surgery on Jan. 16.
Since then, his father has undergone treatment at the same hospital as Kate for an enlarged prostate, before Buckingham Palace announced on Monday that subsequent tests on the 75-year-old monarch had revealed he had a form of cancer.
On Wednesday, William, 41, will make his first public appearance since the series of health blows to the royals when he carries out an investiture – a ceremony where he formally hands out state honours – at Windsor Castle and later attends a gala dinner for London’s Air Ambulance Charity.
With the king postponing public duties as he has out-patient treatment and Kate not expected to return to engagements until after Easter, the onus will be on the remaining royals especially William and Charles’ wife Queen Camilla, to provide the public face of the monarchy.
Royal author Robert Hardman said William had already taken on substantial state duties towards the end of Queen Elizabeth’s reign when she was hampered by mobility issues.
“In that regard, it’s not that different but obviously there’s the burden of expectation,” Hardman told Reuters. “On many occasions he will have to stand in, he’ll be sort of quasi head of state in much the same way that Prince Charles was when the queen was infirm.”
On Tuesday, the king travelled with Camilla to Sandringham House, his home in eastern England, after a brief meeting of about 30 minutes with his estranged son Prince Harry who flew in from California to see his father after the king told him he had cancer.
Harry has barely been on speaking terms with many of the Windsors after his criticism of the monarchy since stepping down from royal duties almost four years ago. A royal source said there were no plans for him to see his elder brother William during his visit to Britain.
Despite the diagnosis, Charles is planning to continue with much of his private work as monarch including his weekly audience with the prime minister and dealing with state papers.
Buckingham Palace has not given any details of the condition other than to say it was not prostate cancer, but said the king was remaining “wholly positive” and looking forward to returning to public duty as soon as possible.