The arme forces of the United Kingdom, commonly known as the British Armed Forces or Her Majesty's Armed Forces, and sometimes legally the Armed Forces of the Crown, encompasses a navy, an army, and an air force. With a reported personnel strength of 429,500 in 2006 (195,900 regular force, 191,300 regular reserve, and 42,300 volunteer reserve), the British Armed Forces constitutes one of the largest militaries in Europe, though only the 26th largest in the world by number of troops. The British Armed Forces however have the third highest expenditure (only behind the U.S. and France) of any military in the world. Their Commander-in-Chief is the British monarch, HM Queen Elizabeth II and they are managed by the Defence Council of the Ministry of Defence. Consistent with longstanding constitutional convention, however, the Prime Minister holds de facto authority over the armed forces.