Queen Elizabeth II and the Duke of Edinburgh invited Kate Middleton's parents, Michael and Carole Middleton, to lunch at Windsor Castle. It was the first time that the Queen and her husband met the parents of their grandson's soon-to-wife.
A Buckingham Palace spokesman told the press that it was a "small gathering, just the queen, the Duke of Edinburgh and possibly a small number of people," believed to be private secretaries.
The Middletons, who first met when they were working for a British airline, are self-made millionaires, thanks to their mail order party supply business, Party Pieces.
Kate was first introduced to the Queen at the wedding of Peter Phillips in May 2008. "It was in amongst a lot of other guests and she was very friendly," Kate said last November in an interview following the announcement of her engagement to Prince William.