Catherine, Princess of Wales, receiving chemotherapy treatment for cancer

In a “personal message” filmed in the gardens of Windsor Castle by the BBC, Catherine told of her “shock” when her condition was discovered after she had major abdominal surgery in January.

She has since been the subject of wild rumours, and Friday’s news prompted Rishi Sunak and Keir Starmer to condemn the “lurid” and “unfair” speculation of recent weeks.

The palace said Catherine had wished to provide a medical update in order to put an end to the speculation sparked by her admission to the London Clinic on 16 January for major abdominal surgery.

She added: “It has been an incredibly tough couple of months for our entire family, but I’ve had a fantastic medical team who have taken great care of me, for which I am so grateful.

It is understood that the cancer diagnosis was the “personal matter” that led to William pulling out from a memorial service for his godfather, King Constantine II, in late February.

The speculation was only fuelled when the first official photograph of the Princess of Wales to be released after her abdominal surgery two months ago was recalled by some of the world’s biggest picture agencies over claims it had been manipulated.