The King and Queen were among guests at the wedding of Peter Phillips, the son of the Princess Royal.
The couple attended the ceremony alongside the Prince and Princess of Wales at All Saints Church in Kemble.
Other guests included Zara and Mike Tindall, and the Duke and Duchess of Edinburgh.
Prince William and Catherine received cheers from the gathered crowds, who had travelled from as far as Ireland.
There were shouts of "hip hip hooray" as bride Harriet Sperling arrived.
Members of the public were held behind metal barriers as they waited outside the church.
Peter Phillips, 48, is the King’s nephew, the son of Anne and her first husband Captain Mark Phillips, and older brother to Zara.
He lives near the church on his mother’s Gatcombe Park estate in Minchinhampton.
Mr Phillips’s engagement to bride Harriet Sperling was announced in August last year.
The pair began dating in 2024.
Ms Sperling arrived at the church with three bridesmaids: Mr Phillips’s daughters Savannah, 15, and Isla, 14, and her own teenage daughter Georgina.
The Duke and Duchess of Sussex were not in attendance.
Other royal guests included Princesses Eugenie and Beatrice, who arrived with their husbands Jack Brooksbank and Edoardo Mapelli Mozzi.
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Mr Phillips was previously married to Autumn. The pair wed at St George’s Chapel in Windsor Castle in 2008, but separated in 2020 after 12 years of marriage.
The wedding took place on the same day as the Epsom Derby, with the King and Queen expected to travel to the racecourse following the ceremony to present the trophy.
Mr Phillips and Ms Sperling were guests of the King and Queen at Royal Ascot in June and joined the royal carriage procession to the Berkshire racecourse.
