The Queen's 90th birthday was marked with gun salutes at Edinburgh Castle and London's Hyde Park on Thursday 21 April. The King's Troop Royal Horse Artillery staged a 41-gun Royal salute at Hyde Park, with 71 horses pulling six First World War-era 13-pounder Field Guns into position for the Royal Salute halfway down Park Lane.

On the word of command, each of the six guns fired blank artillery rounds at 10-second intervals until 41 shots were fired. The horses and riders then collected the guns and escorted them back to Wellington Barracks in Birdcage Walk.

David Cameron has led tributes to Queen Elizabeth II as the "brilliant" British monarch celebrates her 90th birthday. The prime minister described the head of state as a "rock of strength" and thanked her for her public service.

"On behalf of the whole country, I want to wish Her Majesty the Queen a very special 90th birthday. Her Majesty has devoted her entire life to the service of others, representing our country, and carrying out all of her duties with extraordinary grace and humility," Cameron said.