Overview
The Chief Whip is a political leader whose task is to enforce the whipping system, which aims to ensure that legislators who are members of a political party attend and vote on legislation as the party leadership prescribes.
United Kingdom
In British politics, the Chief Whip of the governing party in the House of Commons is usually also appointed as Parliamentary Secretary to the Treasury, a Cabinet position. The Government Chief Whip has an official residence at 12 Downing Street. However, the Chief Whip's office is currently located at 9 Downing Street.
The Chief Whip can wield great power over their party's MPs, including cabinet ministers, being seen to speak at all times with the voice of the Prime Minister. Margaret Thatcher was known for using her Chief Whip as a "cabinet enforcer".
From Wikipedia (CC BY-SA 4.0).