Kate Middleton looked stunning as she appeared for a service of thanksgiving to mark Queen Elizabeth II's 90th birthday Friday. The Duchess of Cambridge wore a powder blue Catherine Walker coat dress and Jane Taylor hat.

Middleton's dress featured a white lace embellishment on the front. She carried a small nude box clutch and teamed her outfit with court shoes. Prince William, Prince Philip, Prince Charles, Prince Harry and Camilla, the Duchess of Cornwall, were also present at the ceremony at St. Paul's cathedral in London. 

Kate Middleton Britain's Prince Harry (right), Kate Middleton and Prince William arrive for a service of Thanksgiving to mark the 90th birthday of Queen Elizabeth at St. Paul's Cathedral in London, June 10, 2016. Photo: REUTERS/Stefan Rousseau/Pool

According to the Daily Mail, Middleton narrowly missed getting her heel stuck in a grate while entering the cathedral with Prince William and Prince Harry. She was reportedly seen laughing with Prince Harry after she realized she had a narrow escape.

While Middleton grabbed all eyes during the event, Queen Elizabeth II arrived for the ceremony wearing a primrose yellow coat and matching dress and hat by Angela Kelly.

queen elizabeth Britain's Queen Elizabeth and Prince Philip arrive for a service of thanksgiving for the Queen's 90th birthday at St. Paul's cathedral in London, June 10, 2016. Photo: REUTERS/Ben Stansall/Pool

The service is the beginning of three days of events to mark the queen's official birthday celebrations Saturday.

During the ceremony, Dean of St. Paul's David Ison thanked the queen for her "dutiful commitment, loving leadership, gentle constancy."