London, UK - King Charles III's cancer diagnosis could spur a reconciliation with his younger son Prince Harry – but the rift with his brother Prince William will be more difficult to heal, royal experts said on Tuesday.

The announcement that 75-year-old Charles was suffering from an unspecified cancer prompted an immediate reaction from the disgruntled US-based prince.

He said he had spoken to his father and would be travelling to London.

Harry touched down in the British capital on Tuesday afternoon, less than 24 hours after the palace made his father's diagnosis public.

Prince Harry Ex-royal press secretary says Prince Harry "has completely changed"

The news sparked immediate speculation it could be a catalyst to heal the family tensions that have blighted the start of Charles's reign.

Royal commentator Richard Fitzwilliams, however, described the rift between Harry, also known as the Duke of Sussex, and the rest of the royal family as "very deep".

Since Harry quit royal duties in 2020 and relocated to California, the family has been increasingly fractured by tensions that have seen a complete breakdown in the once close relationship between Harry and heir to the throne William.

Harry and Meghan Markle criticized his family in a string of high-profile outpourings, including a Netflix series and Harry's blockbuster autobiography, Spare.

Claims by Markle, who is mixed race, in an interview with chat show queen Oprah Winfrey that an unnamed member of the family had expressed concerns about the color of her son Archie's skin before he was born prompted the late Queen Elizabeth II to famously note that "recollections may vary."

An infuriated William also responded that the royals were "very much not a racist family."

The Daily Mail's Richard Kay wrote that the siblings were not believed to have even "exchanged a word" for many months.

William had in fact given up on rebuilding their relationship, he said.

"While Charles has been torn by the conflict between his sons and has longed for a rapprochement, William is convinced that trust, the basis of any relationship, has been utterly destroyed," Kay said.

Another royal watcher, Camilla Tominey of the Daily Telegraph, said she feared the brothers' feud was now too entrenched, held out the hope that they might put their differences aside in order to help their father beat his cancer.

"The one thing they do still have in common is their shared love of their 'darling Pa', the only parent they have left," she said, adding that a royal rapprochement would "certainly help the king on the road to recovery."