The King appeared to be in good spirits as he attended the Royal Windsor Horse Show at Windsor Castle.
Charles, wearing a tweed blazer, a striped tie and brown Serengeti sunglasses, was pictured on Saturday smiling and waving at the equestrian event, which was a favourite of his mother Queen Elizabeth II.
The King was seen in conversation with his brother the Duke of Edinburgh – who is due to attend the Pope’s inauguration on Sunday.
The Duchess of Edinburgh was also in attendance and was pictured meeting stallholders and sampling port during the show.
Carrying a long walking cane, Charles was also seen in conversation with the Crown Prince and Prime Minister of Bahrain Salman bin Hamad Al Khalifa.
The King attended the horse show last year shortly after it was announced that he would be returning to public-facing engagements, indicating the positive effect of his cancer treatment.
The Royal Windsor Horse Show was first staged in 1943 to help raise funds for the Second World War effort.
The inaugural show was attended by members of the royal family including King George VI, Queen Elizabeth (the Queen Mother) and the two young princesses, Elizabeth and Margaret.
Queen Elizabeth II was a passionate fan of the event and would frequently be seen walking among the stalls dressed informally and wearing a headscarf.
The late monarch also entered many homebred horses and ponies in classes at the show.
