Charles’s younger son Harry and his American wife Meghan quit royal duties in 2020 and have since unleashed a string of barbed attacks on the monarchy.
Andrew, the king’s eldest brother, has been frozen out over his past association with the disgraced late US financier Jeffrey Epstein and a related sexual abuse allegation which was settled out of court.
Driven in a state car from Buckingham Palace to Westminster Abbey in London, part of the crowd in a grandstand in front of the palace booed as Andrew went past.
It is the first time Harry has joined his family since subjecting them to a torrent of stinging criticism in his recent memoir “Spare” and in a series of television interviews.
Meghan has remained in California with the couple’s young children, thereby avoiding potentially awkward interactions with her in-laws.
Former British Army captain Harry, who served in Afghanistan, was wearing a morning suit with his medals, while Andrew – who flew Royal Navy helicopters in the 1982 Falklands War – wore his robes as a knight of the garter.
Harry was seen chatting with Edoardo Mapelli Mozzi, husband of his cousin Princess Beatrice, Andrew’s elder daughter.
He also had a quick word with the Archbishop of Canterbury, Justin Welby, after entering the Great West Door.
Welby married Harry and Meghan at St George’s Chapel at Windsor Castle in May 2018.
Both Harry and Andrew were seen smiling as they walked through the abbey to their seats.
They were both placed on the third row – out of keeping with their place in the line of succession to the throne.
Harry is fifth in line to the throne, following his brother Prince William, and William’s three children – Prince George, Princess Charlotte and Prince Louis of Wales.
Andrew is eighth in line, coming after Harry and his children – Prince Archie and Princess Lilibet of Sussex.
Andrew sat at the end of the row next to Beatrice, while Harry sat next to Jack Brooksbank, the husband of Andrew’s younger daughter Princess Eugenie.
