WINDSOR, UNITED KINGDOM - UNDATED: (EDITORS NOTE: This image may be used free of charge, internationally, for 14 days from release, until Friday June 24, 2016.) This handout released by the Buckingham Palace on June 10, 2016 to mark the Queen's 90th birthday, shows Queen Elizabeth II with her husband, The Duke of Edinburgh, and was taken at Windsor Castle just after Easter. (Photo by Annie Leibovitz/Buckingham Palace via Getty Images)
Celebrations abound in the U.K. this weekend for the 90th birthday of Queen Elizabeth II, the nation’s longest reigning monarch—at 63 years.
In actuality, today is the birthday of Prince Phillip, who turns 95. The Queen turned 90 on April 21, but tradition has it that the actual celebration takes place at a later date to take advantage of better weather. This year, the Queen selected the second Saturday of June, the 11th.
Today marks the first day of the three-day celebration. On tap for today’s festivities was a Thanksgiving service at St. Paul’s Cathedral.
Queen Elizabeth II waves as she attends a National Service of Thanksgiving as part of her 90th birthday celebrations at St Paul's Cathedral on June 10, 2016, in London. (Mark Cuthbert/UK Press via Getty Images)
Queen Elizabeth II arrives for a service of thanksgiving at St Paul's cathedral on June 10, 2016, in London. (Stefan Rousseau - WPA Pool/Getty Images)
Joining the Queen at the service were more than 50 members of the royal family, including Prince William, the Duchess of Cambridge, and Prince Harry.
Prince Harry, Catherine, Duchess of Cambridge, and Prince William, Duke of Cambridge attend a National Service of Thanksgiving as part of the 90th birthday celebrations for the Queen on June 10, 2016, in London. (Danny Martindale/WireImage)
Catherine, Duchess of Cambridge, Prince William, Duke of Cambridge, Camilla, Duchess of Cornwall, and Prince Charles, Duke of Cambridge attend the service for Queen Elizabeth II's 90th birthday at St Paul's cathedral on June 10, 2016, in London. (Ian Vogler - WPA Pool/Getty Images)
A topic of much chatter was Kate’s dress. Kate donned a “Julia” wool crêpe coat called “mist blue” by designer Catherine Walker & Co., according to People. Her unique hat was the work of Jane Taylor.
Catherine, Duchess of Cambridge attends a lunch as part of the 90th birthday celebrations for The Queen at The Guildhall on June 10, 2016, in London. (Jeff Spicer/Getty Images)
Also in attendance today were prime minsters, governors and ambassadors from various countries, including UK Prime Minister David Cameron.
Prime Minister David Cameron and Samantha Cameron arrive for a service of thanksgiving for Queen Elizabeth II's 90th birthday at St Paul's cathedral on June 10, 2016, in London. (Stefan Rousseau - WPA Pool/Getty Images)
Britain's Queen Elizabeth II (R) shakes hands with New Zealand's Governor-General Jerry Mateparae (2R) during a reception ahead of the Governor General's lunch in honour of the Queen's 90th birthday at Buckingham Palace in London on June 10, 2016. (JOHN STILLWELL/AFP/Getty Images)
The festivities are set to continue Saturday and Sunday. Scheduled for Saturday is the Trooping the Colour parade, a traditional military parade that will be open to the public, while the royal family watches from Buckingham Palace. On Sunday is the Patron’s Lunch, a large street party for over 10,000 people celebrating the Queen’s patronage of over 600 charities and organizations.
