The government chief whip, whose official title is Parliamentary secretary to the Treasury, is appointed by the prime minister and is responsible to him.
The chief whip has to maintain party discipline and to try to ensure that members of the party vote with the government in important debates.
Along with the other party whips he or she looks after the day-to-day management of the government's business in Parliament.
The chief whip is a member of the Cabinet.
It is customary for both the government and the opposition chief whips not to take part in Parliamentary debates.
The chief whip's official residence is Number 12 Downing Street.