Within the ancient walls of Westminister Abbey, her Majesty will remember the day she was crowned on June 2, 1953, marking the milestone with the nation and her family.
Kate wore the Jane Taylor hat she wore to the jubilee and an elegant nude dress and matching coat from British designer Jenny Packham, one of the Duchess's favourite labels.
As the royal couple arrived with Prince Harry, huge cheers erupted from the crowds gathered in the sunshine.
They were preceded by the Duke of York and his daughters Princesses Beatrice and Eugenie, both of whom failed to disappoint with their flamboyant headwear.
Also present were the Earl and Countess of Wessex and their daughter Lady Louise Mountbatten-Windsor, the Princess Royal and her husband Vice Admiral Sir Tim Laurence.
Other royal guests included Peter Phillips and his wife Autumn, Zara Phillips and her husband the former England rugby international Mike Tindall.
Later the Prince of Wales and the Duchess of Cornwall arrived and waited for the Queen and Duke at the Great West Door.
Inside the ancient place of worship the congregation were shown black and white footage of the coronation on flat screen televisions.
The Duke of Edinburgh missed a royal engagement with the Queen last night because he was feeling "under the weather" but is expected to attend the service, Buckingham Palace has said.
The majestic St Edward's Crown - with which the Queen was crowned - will rest on the High Altar - the first time the heavy, solid gold, jewel encrusted crown has left the Tower of London since the 1953 coronation.
The Ampulla, the gold, eagle shaped bottle from which the holy oil was poured for the anointing - the most sacred part of the coronation - will also stand on the altar.
A flask of aromatic oil - taken from the same batch made for the Queen's coronation - will be processed through the Abbey, carried by representatives of the people of the UK , to the Sacrarium, received by the Archbishop of Canterbury and placed by the Dean of Westminster on the High Altar.
Prime Minister David Cameron is to give a reading, as will the Secretary General of the Commonwealth Kamalesh Sharma.
Actress Claire Skinner, who stars in the BBC sitcom Outnumbered, will read a poem written for the anniversary by the Poet Laureate Carol Ann Duffy.