The King has joked about being “allowed out of my cage” on a visit to an army barracks in Surrey.
As he was being led around, he told the commanding officer: “I do apologise for taking you by surprise, when this opportunity appeared and I had been allowed out of my cage, I wanted to come to have a look.”
The King is thought to have been continuing his cancer treatment as an outpatient this week.
The monarch, who is colonel-in-chief of the Royal Engineers, made the remarks on a trip to 3 Royal School of Military Engineering – at Gibraltar Barracks in Minley.
He appeared in good spirits, telling the wife of one corporal “nothing a strong drink won’t help” when she told him the couple had three children.
The King was given flowers and Royal Engineer mugs from the children of some of the soldiers – and received a portrait of himself from six-year-old Louie Bacon.
The 75-year-old has only recently returned to public duties following the public announcement of his cancer treatment, but he wasn’t the only royal out in the sun on Thursday.
The Queen was pictured with a donkey and Shetland pony at an event celebrating 90 years of equine charity Brooke at Buckingham Palace.
She snapped a carrot in half, asking Alfie the donkey: “Are you greedy?”
Queen Camilla also offered a snack to LaLa the pony and quipped both were “about my size”, before going on to meet some of the charity’s horses.
The Queen has been president of the charity – originally set up for abandoned horses after the First World War – since 2006. It’s helped 1.4 million animals and now works in 15 countries.
In a short speech, she called it “the most remarkable charity”.
The reception came after the Queen hosted the Palace’s first garden party of the year with the King and other royals on Wednesday.
Prince William was also out about on Thursday on a visit to the Cornish coast.
The heir to the throne looked relaxed at Newquay’s Fistral beach as he met groups involved sea and beach safety, watching a demo of surfboard skills and resuscitation drills.
William – who is also the Duke of Cornwall – was pictured taking part in a spot of volleyball with teenagers from a lifesaving group.
The royal earlier stopped by a nearby accommodation scheme for homeless people, run by the Duchy of Cornwall, that will see 24 homes built.
William’s day out comes as Prince Harry is also in the UK after appearing yesterday at an event to mark 10 years of the Invictus Games.
A spokesperson for Harry said he and his father were unable to meet due to a clash between the St Paul’s Cathedral event and the Palace garden party, held just a few miles away.