King Charles makes surprise appearance at Royal Windsor Horse Show without Queen Camilla

King Charles has made a surprise appearance at the Royal Windsor Horse Show today, a regular fixture in the royal calendar.

His wife Queen Camilla, who has dutifully held the fort during the King's cancer treatment, did not join him on this occassion.

Wearing a large parka coat to shield him from the wet weather, the 75-year-old monarch looked in high spirits as he arrived for day three of the event as a spectator.

It marks a further sign that the King's health is improving and he is responding well to treatment, following his return to public-facing duties this week.

The Duke and Duchess of Edinburgh and Princess Anne have attended the show over the past few days, which is running from May 1-5.

The annual event, which attracts enthusiasts from around the world, sees many join together in their thousands on the grounds of Windsor Castle for international competitions in show jumping, dressage, driving and endurance.

This week saw the monarch return to public-facing duties for the first time since he revealed his cancer diagnosis at the start of February.

On Tuesday, the King and Queen met with patients and staff at the University College Hospital Macmillan Cancer Centre in London during their visit.

He has held several private audiences at Buckingham Palace since and marvelled at the Coronation Roll, which provides a handwritten record of a monarch's coronation.

Charles will continue to undertake public appearances over the coming months, but it is unclear how many of the summer’s traditional royal events, including Trooping the Colour and the horse racing at Royal Ascot, the King will attend as his treatment continues.

The palace said last week that doctors were “very encouraged” by the King's progress but his schedule will be adjusted as needed to protect his recovery.