LONDON (AP) - 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 (1100GMT). 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 Feb. 8, 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 Color" military parade.
The "Trooping the Color" tradition dates back to 1748 when George II had the idea to have a public celebration of the monarch's birthday and a parade. When Edward VII took the throne, he continued the tradition. owever, because his birthday was in November, it was decided the public birthday festivities should be in June when the weather is warmer.
From then on, Britain's highest-ranking monarch has gotten two birthdays-- just another perk of being Queen.