Charles was joined by his wife Camilla, the queen consort, and his extended family including son and heir Prince William, his wife Kate and their three children, in a walk from the castle to the nearby St. George’s Chapel.

Also present was the king’s younger brother Prince Andrew, who was removed from royal duties before settling a US sex abuse lawsuit last year.

The occasion, one of the few events which bring all the royals together in public, is particularly poignant this year, being the first since the death of Queen Elizabeth and also falling two years to the day since her husband Prince Philip died. Both are buried in the King George VI chapel at Windsor.

It is also the 18th wedding anniversary for Charles and second wife Camilla, who tied the knot in Windsor in 2005.

As king, Charles is the symbolic head of the Church of England as its Supreme Governor, and the Mail on Sunday newspaper reported that there was disagreement between the monarch and church leaders over the role other faiths might play in his coronation, a solemn religious occasion, on May 6.

The paper said the discussions were delaying the release of the coronation’s Order of Service, but said both Buckingham Palace and the Church had said details would be released in due course while sources had denied there was any delay.