The Office of the Parliamentary Counsel (OPC) is responsible for drafting all government bills introduced to the Parliament of the United Kingdom.

Established in 1869, the OPC is part of the Cabinet Office and led by the First Parliamentary Counsel, Jessica de Mounteney.

William Pitt was the first person to appoint a dedicated parliamentary draftsman, known as the Parliamentary Counsel to the Treasury, who in 1833 described his duties as "to draw or settle all the Bills that belong to Government in the Department of the Treasury",[3] although he also produced bills for other departments.

Despite this many bills continued to be drafted by other barristers, and one of these barristers (Henry Thring) suggested that "the subjects of Acts of Parliament, as well as the provisions by which the law is enforced, would admit of being reduced to a certain degree of uniformity; that the proper mode of sifting the materials and of arranging the clauses can be explained; and that the form of expressing the enactments might also be the subject of regulation".

[4] The OPC was initially part of HM Treasury, but when the Civil Service Department was created in 1969 the OPC became a part of it, changing its name from Office of the Parliamentary Counsel to the Treasury to simply the Office of the Parliamentary Counsel.