Heir to the British throne Prince William, whose wife Catherine is recovering from abdominal surgery and father King Charles III has been diagnosed with cancer, on Tuesday pulled out of attending a memorial service, citing a "personal matter".

It declined to elaborate but said Catherine, the Princess of Wales, continued to be "doing well".

William had been due to attend a memorial service at Windsor Castle, west of London, for the late King Constantine of Greece, who was also his godfather.

The Prince of Wales had called the Greek royal family, who are attending the service, to let them know he was unable to attend, the palace said.

This year has seen a sudden shortage of frontline royals after the almost simultaneous hospitalisation of the king and Catherine earlier this year.

The family's health woes have left William shouldering a heavy burden of public duties while at the same time supporting Catherine and helping care for their three children.

Charles was admitted for surgery for a benign prostate condition last month but subsequently diagnosed with an unrelated cancer.

He has withdrawn from public-facing duties while he undergoes treatment.

Catherine underwent abdominal surgery at the same time and is currently recuperating, following a two-week hospital stay.

Queen Camilla, Charles wife, is attending the memorial service at Windsor's Saint George's Chapel.

King Constantine of Greece died in January 2023.