King Charles, who has been diagnosed with cancer, will reportedly receive "highly specialised" and "less invasive" treatment in London.
The 75-year-old, who is currently resting at Sandringham, is expected to return to London for the treatment.
"Cancer treatment has come on in leaps and bounds in past years and are smarter than was the case previously. The efficacy and side effects are therefore significantly improved," a source told The Mirror.
Prince William's father's public duties have also been postponed to minimise the risk of infection or exposure to viruses while he undergoes treatment.
Other working members of the royal family are expected to rally round during his difficult time.
Meanwhile, Prince William returned to duties on Wednesday carrying out an investiture at Windsor Castle and attending a gala for the London Air Ambulance Charity, alongside Hollywood actor Tom Cruise.
It was first public engagement of the Prince of Wales since the Princess of Wales was admitted to hospital for abdominal surgery on January 16.
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