King Charles attends church in most significant public appearance since cancer diagnosis

The 75-year-old monarch was at the annual Easter Sunday service at Windsor Castle

King Charles III waves as he leaves after attending the Easter Mattins Service at St George's Chapel in Windsor. Getty Images

The 75-year-old monarch leaves St George's Chapel after the service. AFP

The king arrives for his most significant public appearance since his cancer diagnosis. AFP

King Charles III greets well-wishers as he leaves St George's Chapel. AFP

King Charles III and Queen Camilla depart the Easter church service. EPA

The king's attendance at the Easter Mattins Service will be seen as a move to reassure the public. AFP

The Easter service came just over a week after Kate, Princess of Wales announced her cancer diagnosis. EPA

Britain's King Charles III and Queen Camilla meet well wishers as they depart the Easter church service. EPA

The king told well wishers outside the church that they were 'very brave to stand out here in the cold'. EPA

The king reached into the crowd to greet people who waved get-well cards and snapped photos. Reuters

A member of the public told the king: 'We're all rooting for you, we've all got your back'. AP

Charles was applauded by crowds as he and Queen Camilla re-emerged from St George's Chapel to cries of 'Happy Easter'. AFP

The king, dressed in a dark overcoat and shiny blue tie, smiled as he made his way along a rope line outside the chapel. AFP

King Charles III attended church on Easter Sunday in his most significant public appearance since he was diagnosed with cancer.

The 75-year-old monarch shook hands and chatted with onlookers after attending the Easter service at Windsor Castle on Sunday.

Charles was applauded by crowds as he and Queen Camilla re-emerged from St George's Chapel to cries of "Happy Easter", before a young boy presented Camilla with a posy of white and yellow flowers.

The king, dressed in a dark overcoat and shiny blue tie, smiled as he made his way along a rope line outside St. George's Chapel for about five minutes, reaching into the crowd to greet people who waved get-well cards and snapped photos on a chilly early-spring day.

The well wishes follow the announcement of the king's cancer diagnosis, with another member of the public telling Charles on Sunday: "We're all rooting for you, we've all got your back."

The king shook hands and spoke with those who had gathered at Windsor and told them: "You're very brave to stand out here in the cold."

But Kate, Princess of Wales, and her family did not attend as she too continues her treatment for cancer.

King Charles has postponed all previous public engagements since Buckingham Palace announced he was to undergo treatment for an unspecified form of cancer which was found in tests after he had a corrective procedure for an enlarged prostate in January.

Last week the king did not attend an annual Maundy Thursday service but issued an audio message which aired at the event, in which he expressed his sorrow at not being there and wished the public a happy Easter.

The king's attendance at The Easter Mattins Service will be seen as a move to reassure the public after the shock news about his daughter-in-law.

The Easter service comes just over a week after Kate released an emotional video message disclosing that she had started a course of preventive chemotherapy.

Prince William and his wife Kate and their children Prince George, Princess Charlotte and Prince Louis, who all attended last year, are spending the Easter holidays together as they adjust to Kate's diagnosis, which was discovered in post-operative tests after major abdominal surgery.

The service is a smaller version of the annual gathering, with fewer members of the royal family, as the king has paused public-facing duties while he continues treatment for cancer himself.

He was described by the Palace as being “so proud” of the princess for her courage in speaking out, and is said to be in “the closest contact with his beloved daughter-in-law”.

The king's own treatment for cancer was announced at the start of February and he has been carrying out low-key official duties behind palace walls.

He revealed messages of support and cards that he has received since his cancer diagnosis have moved him to tears.

Arrivals at the chapel's Galilee Porch are often watched by staff living at Windsor, who usually gather on a grassy bank nearby or watch from their doorsteps.

Queen Elizabeth II is buried in the church's tiny King George VI Memorial Chapel, with the Duke of Edinburgh and her parents George VI and the Queen Mother.