The Duchess of Cambridge stunned onlookers today in a dress by Alexander McQueen and a hat by Jane Taylor.
Kate chose the nude-coloured, knee-length lace dress with long sleeves for today's service of thanksgiving at St Paul's Cathedral.
Hundreds of well-wishers gathered outside the cathedral ahead of today's service, in which the Archbishop of Canterbury, Dr Rowan Williams, will give the sermon to mark the Queen's 60 years on the throne.
The Duke of Cambridge wore a morning suit to today's service to mark the Diamond Jubilee.
Princess Beatrice wore a Kinder Blue coat dress with tan-coloured Gina stilettos. Her hat was by Stephen Jones while her bag was designed by Lemeresca.
Princess Eugenie wore a purple dress by Suzannah. Her bag was by Loro Piano. Here mushroom-coloured nude stilettos were also by Gina, while her hat was by the same designer as her sister's.
Carly Wood, who set up the katemiddletonstyle.org blog, said the Duchess has worn lace before, most recently an Erdem lace overlay dress called the Cecile when she arrived for last year's royal tour of Canada.
Last September, the 30-year-old future queen wore a mid-length raspberry-coloured lace dress by Collette Dinnigan to the wedding of her friends Thomas Sutton and Harriet Colthurst at a church in Wiltshire.
Miss Wood, 26, from Leeds, said the Duchess today matched the nude Alexander McQueen dress with her L.K. Bennett sledge heels.
She said: "We've seen Kate in McQueen for every event over the weekend so far. She is very fond of the designer.
"I think she looks very feminine in the dress, which is both pretty and elegant and I think Kate's pearl earrings set off the dress nicely.
"She chose a sleeved, knee-length dress in an understated, pale colour, which is appropriate for the occasion.
"A repeat of the bright red, for example, would have taken too much attention away from the Queen today, especially as the Queen is wearing a pastel mint colour today.
"I have a very slight criticism - as soon as I heard Alexander McQueen and saw the lace it took my mind back to her wedding day.
"Perhaps I think things through too much, but I personally would have stayed away from wearing Alexander McQueen and lace on the Queen's big day, knowing that newspapers and magazines will make the connection and write about it.
"The dress already appears to be a hit on Twitter and I think it will spur a lot of ladies to try and 'repliKate' the look for weddings, services and events up and down the country this year."