The Prime Minister appoints about 20 senior MPs to become ministers in charge of departments. These include the Chancellor of the Exchequer, responsible for the economy, the House Secretary, responsible for law, order and immigration, the Foreign Secretary, and ministers (called ‘Secretaries of State’) for education, health and defence. The Load Chancellor, who is the minister responsible for legal affairs, is also a member of the Cabinet but sat in the House of Lords rather than the House of Commons. Following legislation passed in 2005, it is now possible for the Load Chancellor to sit in the Common. These ministers from the Cabinet, a small committee which usually meets weekly and makes important decisions about government policy which often then have to be debated or approved by Parliament..
(Source: 2nd Edition, Life in the United Kingdom)