Diana, Princess of Wales and her eldest son Prince William are seen waiting for Prince Harry after attending the annual Easter Sunday church service at St.Georges Chapel inside Windsor Castle, west of London in this April 19, 1992 file photograph.[Photo/Agencies]

Diana, Princess of Wales, accompanied by her son Prince William (R), is seen arriving at Wimbledon's Centre Court before the start of the Women's Singles final in London in this July 2, 1994 file photograph.[Photo/Agencies]

She described the proposal this way: "It was very romantic, and it was very personal."

The union has important implications for the monarchy's line of succession. Kate and William's first child would move ahead of his younger brother, Prince Harry, to become third in line to the throne.

Middleton acknowledged that being queen was "a daunting prospect." She declined to say whether the prince had gone down on bended knee when he proposed.

The two met as freshmen at the University of St. Andrews in Scotland, starting out as just friends but quickly becoming boyfriend and girlfriend.

"Obviously we both have a very fun time together, both have a very good sense of humor about things. We're down to earth ... and she's got plenty of habits that make me laugh that I tease her about," William said as he and Middleton faced photographers earlier Tuesday.

There is no firm date for the wedding, and the venue has not been specified. Speculation focused on St. Paul's Cathedral and Westminster Abbey.

It is not yet clear whom the elegant Middleton will choose as a dress designer, and the royal titles the couple will assume when they become man and wife have not yet been revealed.

The marriage will link Middleton — whose parents, self-made millionaires, founded a successful mail-order party supply business after working in the airline industry — with William, scion of one of the richest families in the world.

Midddleton attended Marlborough College, an elite private school, where she played tennis and field hockey, before studying art history at St. Andrews. After graduating in 2005, Middleton worked as a buyer for the fashion chain Jigsaw. She is now employed by her family's party-planning business.

William has tried to lead a normal life, training to become a military helicopter rescue pilot, but has also become accustomed to extravagant vacations at the world's most exclusive hideaways.