position in the constitutional hierarchy in relation to the sovereign, Parliament and Cabinet. Before 1902, the prime minister sometimes sat in the House of Lords, provided that his government could form a majority in the Commons. However, as the power of the aristocracy waned during the 19th century the convention developed that the prime minister should always sit as a Member of Parliament in the lower house, making them answerable only to the Commons in Parliament. The prime minister's authority was further enhanced by the Parliament Act 1911, which marginalised the influence of the House of Lords in the law-making process. Authority, powers and constraints The prime minister is the head of the United Kingdom government. As such, the modern prime minister leads the Cabinet (the Executive). In addition, the prime minister leads a major political party and generally commands a majority in the House of Commons (the lower chamber of Parliament). The incumbent wields both significant legislative and executive powers. Under the British system, there is a unity of powers rather than separation. In the House of Commons, the prime minister guides the law-making process with the goal of enacting the legislative agenda of their political party. In an executive capacity, the prime minister appoints (and may dismiss) all other Cabinet members and ministers, and co-ordinates the policies and activities of all government departments, and the staff of the Civil Service. The prime minister also acts as the public "face" and "voice" of His Majesty's Government, both at home and abroad. Solely upon the advice of the prime minister, the sovereign exercises many statutory and prerogative powers, including high judicial, political, official and Church of England ecclesiastical appointments; the conferral of peerages and some knighthoods, decorations and other important honours. Constitutional background The British system of government is based on an uncodified constitution, meaning that it is not set out in any single document. The British constitution consists of many documents and most importantly for the evolution of the office of the prime minister, it is based on customs known as constitutional conventions that became accepted practice. In 1928, Prime Minister H. H. Asquith described this characteristic of the British constitution in his memoirs:In this country we live ... under an unwritten Constitution. It is true that we have on the Statute-book great instruments like Magna Carta, the Petition of Right, and the Bill of Rights which define and