By Ian Casey, BBC News
King Charles waves to crowds outside St George's Chapel at Windsor Castle on Easter Sunday. Photo: Samir Hussein/WireImage
King Charles has arrived at the Easter service in Windsor in his first major public appearance since being diagnosed with cancer.
The King smiled and waved as he walked into the service at St George's Chapel accompanied by Queen Camilla.
The Prince and Princess of Wales are not attending, as Catherine continues her cancer treatment.
The King has continued some work since his diagnosis, but all engagements so far have taken place in private.
Earlier this week he spoke of his "great sadness" at missing the traditional Maundy Thursday service, which was instead attended by Queen Camilla.
The King's attendance at the Easter morning church service will be seen as an encouraging sign about his health.
The BBC understands this does not mark the start of a return to public duties, but instead a careful first step back into the public eye.
The King was seen arriving in a car with Queen Camilla.
The Duke and Duchess of Edinburgh, their son James, Princess Anne and her husband Timothy Laurence, and the Duchess of York were all seen arriving just before the King and Queen. Prince Andrew was not seen among the group.
Last year marked the King's first Easter Sunday service as monarch.
The King has not been at public events this year. His cancer was detected while he was undergoing treatment for an enlarged prostate in January. While the type of cancer has not been disclosed, Buckingham Palace has confirmed it is not prostate cancer.
He attended church in Sandringham in February, shortly after his diagnosis. Well-wishers gathered as the King walked into the church, which is on his private estate in Norfolk, but were not allowed to enter the grounds which are closed to the public until Easter.
Meanwhile, earlier this month, the Princess of Wales revealed in a video announcement that she is undergoing preventative treatment for cancer.
Catherine had abdominal surgery in January, when it was not known there was any cancer, but subsequent tests found it had been present.
There is no early return to official duties expected for the princess.
Neither the King's or Catherine's type of cancer has been revealed.
The diagnoses have depleted the ranks of working senior royals.
Queen Camilla has led the line for the royals for the past few months, increasingly carrying out trips on her own that would once have been the responsibility of her husband.
Prince William has kept up projects such as Earthshot and Homewards, but is likely to limit his travels to stay close to home and protect some kind of normal family life.
It is not known how future key dates in the royal calendar, such as Trooping the Colour in June, will be represented by members of the Royal Family, or when the King will return to public engagements.
- This story was first published by the BBC.