London — Britain is marking Queen Elizabeth II's 91st birthday with gun salutes, as the monarch celebrates quietly at home.
A troop of the Royal Horse Artillery will ride horse-and-gun carriages past Buckingham Palace before staging a 41-gun salute in Hyde Park at noon (11:00GMT). There will also be a 62-gun salute at the Tower of London an hour later.
The queen is Britain's oldest and longest-reigning monarch, having become queen on 8 February 1952. She is also the world's longest-reigning living monarch since the death of Thailand's King Bhumibol Adulyadej last year.
The queen usually spends her birthday privately. She also has an official birthday, marked in June — when the weather is better — with the "Trooping the Colour" military parade.