The chancellor of the exchequer is the government's chief financial minister and as such is responsible for raising government revenue through taxation or borrowing and for controlling overall government spending.
The chancellor's plans for the economy are delivered to the House of Commons every year in the Budget speech.
The chancellor is the most senior figure at the Treasury, even though the prime minister holds an additional title of "First Lord of the Treasury".
He normally resides at Number 11 Downing Street.
However Gordon Brown, during his tenure as chancellor, lived at Number 10 and worked at Number 11.
He swapped living quarters with then Prime Minister Tony Blair who required a larger house than Number 10 for his family.
Great office of state
The exchequer itself was originally just a large table, 10 feet by 5 covered by a chequered cloth that operated as a form of abacus.
In the 12th century the role of chancellor was little more than that of an admin clerk.
The position gained more power and authority as the Treasury grew and the tax system got more complicated.
Now along with prime minister, foreign secretary and home secretary it's regarded as one of the four great offices of state.