Duchess Kate, Prince William, Prince Harry Lead the Royal Troops at Queen Elizabeth’s 90th Birthday Celebrations

Catherine, Duchess of Cambridge, and Prince William attend a National Service of Thanksgiving as part of the 90th birthday celebrations for the Queen at St. Paul’s Cathedral on June 10, 2016, in London. Getty Images

A perfectly formal occasion. Duchess Kate was joined by husband Prince William and brother-in-law Prince Harry as she arrived at London’s St. Paul’s Cathedral on Friday, June 10, to attend a celebratory 90th birthday service for Queen Elizabeth II.

Looking stunning in a pale blue Catherine Walker creation, Kate Middleton wore her hair up in a loose ponytail, sporting a white pillbox hat by milliner Jane Taylor to top off her pretty, formal attire.

Prince Harry, Duchess Kate and Prince William arrive at St. Paul’s Cathedral. Danny Martindale/WireImage

The royal trio were joined by 50 other members of the royal family, including Prince Charles, the Duchess of Cornwall, Princesses Beatrice and Eugenie of York and Mike and Zara Tindall, in addition to an array of British dignitaries, including Prime Minister David Cameron.

As they walked into the magnificent cathedral, the Duchess of Cambridge giggled as Prince Harry whispered something in her ear. The close family members took their seats as they awaited the arrival of Queen Elizabeth and her husband, Prince Philip, who arrived 11 minutes late due to London traffic.

Kate Middleton, Prince Harry
Prince Harry and Duchess Kate share a joke as they arrive at St. Paul’s Cathedral. Matt Dunham - WPA Pool/Getty Images

The British monarch wore a primrose yellow outfit by Angela Kelly to the majestic event — a national service of thanksgiving to celebrate her life and that launches a weekend of events marking her 90th birthday, which was on April 21.

In addition to marking the Queen’s significant birthday, her husband, Prince Philip, is also celebrating his birthday today. The Queen’s consort, who turns 95, will be honored later with a traditional gun salute.

Following the cathedral service, the Queen, the Duke of Edinburgh, Prince Charles and the Duchess of Cornwall hosted a lunch for the Governors General of all Commonwealth Realms at Buckingham Palace.

Her majesty’s official birthday will also be honored on Saturday, June 11, at the annual Trooping the Colour ceremony. On Sunday, June 12, the Patron’s Lunch (a 10,000-person event that celebrates the Queen’s patronage of more than 600 organizations) will complete the jam-packed weekend.

The royal family previously celebrated the Queen’s birthday in May with a star-studded two-hour event that aired live on U.K. television.

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