The job of the prime minister as the head of a parliamentary government is to make policy and final decisions regarding the state, to select members of the cabinet and to assign posts to members within the government. England and Canada are examples of countries with prime ministers.
The prime minister is the most senior minister of the cabinet in the executive branch of government in a parliamentary system. In such systems, the prime minister is usually the presiding member and chairman of the cabinet. In countries that have a semi-presidential system of government, the prime minister manages the civil service and governmental agencies and executes the laws.
In England, the role of prime minister is based on the original ministerial positions, assumed by multiple men, each of whose job it was to serve the king in various capacities. Ministers sometimes also acted as confidants to their sovereign. For example, Thomas Cromwell served King Henry VIII as his chief minister. William Cecil and Lord Burghley served Queen Elizabeth I and were considered more like chief advisers. After the English Civil War, the passage of the Bill of Rights and the death of Queen Anne I, Parliament gained power, and the chief minister at that time continued the rule of England.