Originally, the king or queen could choose anyone they liked to be chief or ‘Prime’ Minister, and for a long time the prime minister could come from either the House of Lords or the House of Commons . In recent years the Prime Minister has always come from the Commons and the king or queen gives the job to the leader of the party with the largest number of MPs . Lord Home, who became leader of the Conservative Party in 1963, was the first politician to be allowed to renounce a peerage (= give up an inherited title and status) to become Prime Minister as Sir Alec Douglas-Home ).
The Prime Minister is by tradition First Lord of the Treasury and Minister for the Civil Service. He or she chooses and presides over the Cabinet and heads the government. The Prime Minister chooses senior ministers and recommends their appointment to the king or queen. While other ministers are responsible for particular government departments , the prime minister is concerned with policy as a whole. Cabinet committees usually report directly to him or her. The Prime Minister has regular meetings with the sovereign to inform him or her of the activities of the government.
The prime minister lives at 10 Downing Street , above the offices used by the Cabinet, and is often photographed outside the front door.