Kate is regal in red on the Royal Barge03 JUNE 2012
It was one of the most significant moments in the Duchess of Cambridge's life as a royal so far.
Accompanied by her husband Prince William, the beautiful brunette was by the Queen's side as the monarch was feted by a million people for the second longest reign in British history.
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And as Kate joined other senior members of the Windsor clan royals on the Thames she certainly looked the part.
Regal in red, the 30-year-old had chosen Alexander McQueen.
Her dress fell in pretty sunray pleats from her slim hips and was topped off with a Sylvia Fletcher hat in the same vivid scarlet hue.
Alexander McQueen, the fashion house chosen to create her beautiful wedding dress, is one of Kate's go-to designers.
And while this particular frock has been seen before on Kim Kardashian and Tulisa, Kate made sure to put her own elegant stamp on it.
Her version, mid-length rather than pop star short, also had long sleeves making it appropriate for such a historic occasion.
Later, because of the freezing conditions, the Duchess added a scarf in the new Strathearn tartan created just after the royal wedding, when she and William were also created the Earl and Countess of Strathearn.
Her husband, meanwhile, was dashing in his RAF uniform — the Flight Lieutenant No. 1 complete with a blue garter sash.
And his brother, Prince Harry, looked equally handsome in the No. 1 Ceremonial dress of the Blues and Royals and an Army Air Corps light blue beret.
The trio were on the royal barge during the water extravaganza, which saw a flotilla of 1,000 ships, boats, yachts and other vessels take to the river.