Self portraits by 200,000 children are projected onto Buckingham Palace to form portraits of Queen Elizabeth in central London April 19, 2012. The portraits were collected by the Prince's Foundation for Children and the Arts to celebrate the nation's children in the run up to the London 2012 Olympic and Paralympic games and the Queen's Diamond Jubilee. [Photo/Agencies]

Military units across the country fired gun salutes to mark the occasion, with a 41-gun salute fired by horse-drawn artillery in central London's Hyde Park, and a 62-gun salute fired at the Tower of London by the Royal Gibraltar Regiment.

Other venues for gun salutes included York in the north of England, and Windsor, home to the Queen's residence Windsor Castle.

To mark the birthday, the Queen announced the Queen's Awards for Enterprise, which reward achievement by businesses.

The Queen stuck with tradition this year, and spent her birthday privately celebrating with members of her family at Windsor.

A public celebration of her birthday is held each year in the middle of June, on her official birthday.

This is not the same day each year, but always a Saturday in the first half of June when the fickle British weather is most likely to provide good weather for the celebrations.

Each year on the official birthday, the Queen inspects military units from her own division of the British Army, the Household Division.

The units, representing five battalions of Foot Guards, a battalion of cavalry and a battery of artillery, march through central London in ceremonial uniforms and then parade in front of the Queen.

As the Queen celebrated her birthday, a row was developing over the re-release of an anti-monarchist song "God Save the Queen" by punk band the Sex Pistols.

The single was originally released in 1977 to mark the then Silver Jubilee of the Queen, and included the lyrics "God Save the Queen/She ain't no human being." It became an anti-establishment hit, and provoked widespread anger among authorities.

The BBC banned the song, local authorities refused to allow the band to perform shows, and many shops would not sell the single.

Members of the Sex Pistols were briefly arrested for playing the song on a boat sailing down the Thames river in London during the Silver Jubilee celebrations on June 7, 1977.

The record company Universal announced plans to re-release the song at the beginning of June, but the band's lead singer John Lydon disassociated himself from the re-release and urged fans not to buy the single.