The 99-year-old Philip, Queen Elizabeth II's husband, has been Colonel-in-Chief of The Rifles since 2007 and has served in the same role for earlier regiments that have made up the infantry unit since the 1950s.
Camilla, the Duchess of Cornwall, stands with Colonel Commandant, General Sir Patrick Sanders, at Highgrove House, during the military ceremony.
On Wednesday, Camilla, Prince Charles' wife, was welcomed as the regiment's new colonel-in-chief in a separate ceremony.
Philip retired from public duties in 2017. He was pictured at Windsor Castle with the queen to mark his birthday in June, and he attended Princess Beatrice's private wedding ceremony on Friday.
He was last seen at a big event when he was a guest at Lady Gabriella Windsor's wedding in May 2019.
