08/21/2000 at 01:00 AM EDT
Any British subject who reaches the age of 100 receives a birthday card from the Queen. But only one of the 12 who marked that milestone Aug. 4 got a card signed "Lilibet" (Elizabeth II's childhood nickname) or had an Irish Guardsman on hand to open the envelope with his sword. After receiving the Queen's personal postman at her London home, the royal matriarch joined grandson Prince Charles for a carriage ride to Buckingham Palace. There, with 27 family members, including daughters Queen Elizabeth and Princess Margaret, she waved from a balcony as 40,000 well-wishers sang "Happy Birthday." After lunch at the palace, the centenarian hit the Royal Opera House to see the Kirov Ballet. Says fan Constance Whittington, 60: "She has amazing stamina."
She asked a guardsman to open her card: "Can you use your sword?"
Tony Blair praised the Queen Mum (with Charles, en route to Buckingham Palace) for her "sense of duty."
Royal kin on the palace balcony (from left): Zara Phillips, Commodore Timothy Laurence, Princess Anne, Peter Phillips, Princess Beatrice, Prince Andrew, Princess Eugenie, Princess Margaret, the Queen Mum, Queen Elizabeth, Prince Edward, Prince Philip (obscured), Sophie, Countess of Wessex, Prince William
, Prince Charles, Prince Harry
and Princess Michael of Kent.