Prince Harry and Meghan Markle were booed as they left St. Paul's Cathedral on Friday morning.
The couple attended Queen Elizabeth II's Service of Thanksgiving, an event included in Her Majesty's Platinum Jubilee. The queen herself was not in attendance due to "some discomfort" she experienced on Thursday.
Markle and Harry left the church to boos, while Prince William and Kate Middleton received cheers.
The 40-year-old former actress wore a monochrome outfit in cream. She accessorized with closed-toe pumps, a hat and gloves.
The official birthday of the queen kicked off Thursday with Trooping the Colour and the lighting of the beacons. Friday's main event was the Service of Thanksgiving, which occurred in the morning at St. Paul's Cathedral.
The Service of Thanksgiving is one event of many to occur throughout the week and weekend as Britain celebrates 70 years of Queen Elizabeth II's reign. It follows Silver, Gold and Diamond Jubilee celebrations in 1977, 2002 and 2012, which marked 25, 50 and 60 years on the throne. Jubilees are usually marked with a combination of ceremonial military displays, a church service and street parties.
The events began on June 2 and will continue through June 5.
The Service of Thanksgiving was attended by Prince Charles, Prince William, Kate Middleton, Prince Harry and Markle.
Prince Andrew was notably absent after testing positive for COVID-19.
Lord lieutenants were in attendance to represent every country of the U.K., alongside the prime minister, members of the cabinet, first minister of the devolved governments and leaders of the opposition, as well as former prime ministers.
Reps from overseas territories and governors general, among others, also were in attendance.
The Associated Press contributed to this report.