Kate and Beatrice travelled together in the second carriage of the procession, with Kate dressed in a striking red Alexander McQueen outfit and Philip Treacy hat.
William meanwhile was dressed smartly in a morning suit and top hat like the other royal men.
Beatrice, who joined Kate and William in their carriage with her husband Edoardo Mapelli Mozzi, stunned in a white lace gown with floral details, as she and Kate arrived together just as Diana and Fergie did in 1990.
On that day at Ascot 33 years ago Diana and Fergie also stepped out in bold red outfits, with Diana teaming her red jacket with a mid-length purple skirt by Catherine Walker and a matching Philip Somerville hat.
Fergie meanwhile accessorised her red suit with a red and pink hat, a colour scheme which Beatrice mirrored with the pink floral detail on her gown.
Kate, William, Beatrice and Edo arrived together in the second carriage of the royal procession, with the King and Queen travelling in the first alongside the Duke and Duchess of Devonshire.
In the third carriage was the Duchess of Edinburgh, Earl of Caledon, and the Prince and Princess of Kent.
Then in the fourth carriage came Dame Judi Dench, Mr David Mills, and Mr and Mrs Williams Farish.
Kate and William are based not far from the Berkshire racecourse at Adelaide Cottage, where they are raising their three children Prince George, Princess Charlotte and Prince Louis away from London.
The Wales’s were often guests of the late Queen Elizabeth at Ascot, whose passion for horseracing was well-known as she had over 20 winners at the racing festival over the years.
Charles and Camilla were visibly emotional as their horse crossed the line to secure their first win at Royal Ascot on Thursday.
Desert Win rode to victory in the King George V Stakes ridden by Tom Marquand as the King and Queen cheered on from the royal box.
