Kate Middleton hopes Prince George and Princess Charlotte are well-behaved at Pippa's wedding

With just a few days until her younger sister’s wedding, Kate Middletonexpressed her excitement for Pippa Middleton and James Matthew’s highly-anticipated nuptials. While at the first Buckingham Palace garden party of the season on Tuesday, the Duchess of Cambridge chatted with partygoer Andrew Bates and his wife Janet about her sibling’s big day, admitting that she is looking forward to the wedding, but is slightly nervous about how her young children, Prince George, three, and Princess Charlotte, two, are going to behave.

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Kate admitted she is slightly nervous about how her children are going to behave at Pippa's wedding Photo: Twitter/@KensingtonRoyal

“[Kate] said that they were all really looking forward to her sister's wedding at the weekend but she was a bit worried about how her children might behave," Andrew revealed. "She said she was hopeful that they would be good but you never know at that age.” It was previously announced that her children will serve as a pageboy and bridesmaid in their aunt’s upcoming wedding. Pippa and her fiancé are set to tie the knot on May 20 at Mark’s Church in Englefield, Berkshire, followed by a reception at the Middleton family home in Bucklebury, seven miles away from the church.

MORE: EVERYTHING WE KNOW ABOUT PIPPA'S WEDDING

Members of the royal family attended the first garden party of the season on May 16 Photo: Victoria Jones - WPA Pool /Getty Images

While Saturday will be a family affair for the Duchess, Tuesday was business as usual for the British royal. Kate looked sophisticated at the May 16 party stepping out wearing her ice blue Christopher Kane coatdress, which she previously wore to the Opening Ceremony of the 2012 London Olympics and again in 2014 for the Order of the Garter. The mom-of-two opted for an elegant updo, which she topped off with a pale blue Lock & Co "Sweet Delight" hat.

Prince William changed into more formal attire after his day visiting the Royal Marsden hospital Photo: Victoria Jones - WPA Pool/Getty Images

Along with Kate and the 8,000 guests at Buckingham Palace, a number of royal family members stepped out for the occasion including Her Majesty, the Queen, Prince Philip, Princess Anne, Prince Edward, Princess Beatrice, in addition to Prince and Princess Michael of Kent. Prince William also joined his wife after his visit to the Royal Marsden hospital.

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Guests at the royal-studded event were treated to around 20,000 slices of cake, 20,000 sandwiches and over 27,000 cups of tea. Tuesday’s garden party marked the Queen’s first of four this summer. 30,000 People are expected to attend the parties this season.

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