Members of the public who attended an Easter Sunday church service with the King have said he looked well and in “good spirits”.

Charles attended the service at St George’s Chapel in Windsor Castle with the Queen in what was his most significant public appearance since his cancer diagnosis.

He shook hands and spoke with those who had gathered at the castle in a surprise walkabout following the service, and told them: “You’re very brave to stand out here in the cold.”

Alethea Kilgore, an opera singer from the US who attended the Easter Mattins Service, told the PA news agency: “I think it’s really significant (Charles’ attendance).

“It indicates that he’s doing good and that he’s definitely on the incline in relation to his health, so that’s really nice to see.

“I also would like to thank him for attending the service today because I know that must’ve been a lot, but he shows himself to be committed to this nation and to people all around the world.”

Ms Kilgore said seeing the King on his walkabout after the service was “a really wonderful experience”.

She added: “I wasn’t sure if I was going to be able to see him that closely today, but I certainly did.”

Henry Wood, 20, a private wine merchant from Basingstoke, also attended the service inside St George’s Chapel with his family.

He said: “It was a very nice Easter service, very enjoyable. It was nice to see the King in good spirits and the whole family in good spirits, as if nothing was wrong.

“Obviously it being his first appearance in quite some time, I think people wanted to see him for that reason.

“He looked good today and in high spirits, and from what I’ve heard he’s doing good so it’s refreshing to hear.”

Mr Wood said the service itself was “wholesome” and praised the “exceptional” choir.

Speaking about the rendition of the national anthem, he added: “It was a proud moment, I think. It was the first time I’ve got to sing it in the room with the King.”

Anne Daley, 65, from Cardiff, Wales, held up a Welsh flag when the King arrived and was the first to speak to him when he re-emerged for his walkabout.

She said: “Did you see the smile (Charles) gave me? He pointed at my flag.”

Ms Daley added: “He had a lovely smile. He looked well. I think he was happy that we’ve all come.”