In the past, gun salutes were performed to express friendly intentions, for it indicated that no weapons were hidden. Nowadays its symbolic meaning has slightly changed, and gun salutes are mainly associated with special Royal occasions and represent respect and acceptance. Gun Salutes take place on a number of Royal anniversaries, including Accession Day on February 6, the Queen's birthday on April 21, the Coronation Day on June 2, the birthday of the Duke of Edinburgh on June 10, the birthday of the Prince of Wales on November 14, and other occasions such as the State Opening of Parliament celebrated either in November or December.
Royal salutes at the Tower of London
The gun salutes are fired from different locations. Come at 1 pm to the Tower of London. The Honourable Artillery Company will fire salutes from four 25-pounder guns on Tower Wharf facing the River Thames.
Royal salutes at Hyde Park / Green Park
Also, at noon similar gun salutes happen either at Hyde Park or Green Park—this depends on the occasion. The King's Troop, Royal Horse Artillery fire the salute from six 13-pounder guns.
The basic gun salute features 21 rounds fired at ten-second intervals. Whereas, Hyde Park boasts an extra 20, as it's a Royal Park.