After the Trooping the Colour the King's Troop Royal Horse Artillery fired a 41-gun salute in Green Park to mark the Queen's official birthday.
The royals then gathered on the balcony at Buckingham Palace to watch the traditional RAF flypast.
Thousands of spectators crowded around the front of the palace and on The Mall, many cheering as a succession of planes roared overhead.
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Queen Elizabeth II is to celebrate her 92nd birthday with a star-studded line-up at the Royal Albert Hall in London.
Both figures were not taken seriously before being appointed to their huge roles, but the similarities don't stop there.
The US president, who has not visited the UK since being elected, is reported to be planning a summer trip to Britain.