Chief Secretary to the Treasury

The Chief Secretary to the Treasury (CST) is the most senior deputy finance minister in the United Kingdom. 
The post nominally ranks as the third highest ministerial office in the Treasury. CST is after the First Lord of the Treasury (being Prime Minister) and the Second Lord of the Treasury (being Chancellor of the Exchequer). However, the role of Lord Chancellor of the Exchequer is always held by the prime minister, who is nominally only within the Treasury. 
The office was created in 1961. This was made to share responsibility for representing the Treasury with the Chancellor of the Exchequer.