The King has been diagnosed with a form of cancer and has begun a schedule of regular treatments, and while he has postponed public duties he “remains wholly positive about his treatment”, Buckingham Palace said.

The diagnosis comes after the 75-year-old monarch was recently admitted to hospital because of an enlarged prostate, although the palace says he does not have prostate cancer.

At that time, the Palace told the public: “In common with thousands of men each year, the King has sought treatment for an enlarged prostate.

“His Majesty’s condition is benign, and he will attend hospital next week for a corrective procedure. The King’s public engagements will be postponed for a short period of recuperation.”

The King was eventually discharged after spending three nights in a Central London hospital.

Following his stay at the medical facility, a spokesman said: “The King was this afternoon discharged from hospital following planned medical treatment and has rescheduled forthcoming public engagements to allow for a period of private recuperation.”

Sources close to the Royal Family praised The London Clinic for the security measures put in place during Charles and Kate Middleton's stay.