The Duchess of Cambridge, née Kate Middleton, stepped out for her second engagement of the day on Tuesday afternoon.
Kate, 32, was attending the Queen's second garden party of the year at Buckingham Palace.
The brunette beauty had paid a visit to the National Maritime Museum in Greenwich earlier in the day, and opted to change into more formal wear for the outdoor bash.
The Duchess of Cambridge arrives at the Queen's garden party
Always one to recycle her beautiful outfits, Kate looked radiant in a pale cream, lace Alexander McQueen dress that she had previously worn at a St Paul's Jubilee Service in 2012.
The mum-of-one accessorised with a matching Jane Taylor hat and her favourite nude, court heels.
As Kate soaked up the sunshine and chatted to guests in the gardens, she was spotted close to the royal hosts of the day — the Queen and Prince Philip — who was celebrating his 93rd birthday.
The Queen and the Duke of Edinburgh make their grand entrance
The trio made every effort to cover different areas of the grounds so that they could speak to as many members of the public as possible, and later reconvened in the royal tea tent.
At a typical garden party organised by the reigning monarch, around 270,000 cups of tea, 20,000 sandwiches and 20,000 slices of cake are consumed, with a special tea blend called the "Buckingham Palace Garden Party Tea" prepared.
Members of the British royal family take it in turns to attend the Queen's parties, with Kate originally scheduled for the third event on Thursday. The Duchess had to change her schedule last minute and attend on Tuesday instead.
The Duchess of Cambridge accessorised with a Jane Taylor hat
The celebration may have been a fitting option for Kate anyway, as it meant that she could spend the afternoon celebrating with birthday boy Prince Philip.
At the first garden party held at the end of May, Princess Beatrice was spotted in attendance with her grandparents.
The Queen's parties are considered a highlight of the British social calendar, with a select guest list of around 10,000 people expected at each one. Her Majesty hosts at least three at Buckingham Palace each year and one at her Scottish residence Holyrood House.
Attendees, who have usually contributed to society or charities in a particular way, are also invited to explore the gardens which are not normally open to the general public.