At the age of just twelve, Princess Anne took on the big responsibility of chief bridesmaid for the Queen's cousin Princess Alexandra.
Alexandra married her husband Sir Angus Ogilvy in 1963 in a breathtaking ceremony at Westminster Abbey in front of royals such as the Queen, Prince Philip, Prince Charles and Princess Margaret.
Photos show a young Princess Anne looking beautiful in her simple bridesmaid's dress which featured cropped sleeves and a bow at the waist, paired with a white headpiece that wrapped around her elegant bun.
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Her Majesty's only daughter appeared to be one of seven bridesmaids and page boys that made up Princess Alexandra's bridal party. While the other younger bridesmaids were dressed in the same outfit as Anne, the page boys looked smart in kilts and white shirts.
Princess Alexandra and Sir Angus Ogilvy's bridal party
Anne was pictured with the bride at St James's Palace during the wedding reception, showing off Princess Alexandra's bridal dress designed by John Cavanagh. It featured a high neck and pretty lace, shipped over from France.
In the photograph, the pair were admiring a gold bangle given to Alexandra as a present. Unfortunately, some of her wedding presents were later stolen from her home Thatched House Lodge in Richmond Park, which she shared with her husband Angus and her two children James and Marina.
The young royal was chief bridesmaid for Princess Alexandra
During a robbery, thieves stole £6,000 and a gold cigarette case that was given to Angus by the Queen and the Duke of Edinburgh.
Princess Alexandra's wedding was not the first time Princess Anne had been a bridesmaid. Three years before, the royal was part of the bridal party at the 1960 wedding of Lady Pamela Mountbatten, first cousin of Prince Philip, and David Nightingale Hicks.
On this occasion, the royal's outfit featured a dress with a lace tiered skirt and a satin sash, finished off with a flower crown in her hair.