First Lord of the Treasury
The First Lord of the Treasury is the head of the Lords Commissioners of the Treasury exercising the ancient office of Lord High Treasurer in the United Kingdom. Constitutional convention holds that the office of First Lord is held by the Prime Minister. The office is not the United Kingdom's finance minister; this role is instead held by the Chancellor of the Exchequer, who is the second lord of the Treasury.
First Lord of the Treasury
The front door of 10 Downing Street, showing the letter-box inscribed with "First Lord of the Treasury"
Lords Commissioners of the Treasury
In the United Kingdom there are at least six Lords Commissioners of His Majesty's Treasury, serving as a commission for the ancient office of Treasurer of the Exchequer. The board consists of the First Lord of the Treasury, the Second Lord of the Treasury, and four or more junior lords acting as whips in the House of Commons to whom this title is usually applied.
The door of 10 Downing Street, with "First Lord of the Treasury" inscribed on the letterbox as the addressee for post