Council of Civil Service Unions v Minister for the Civil Service (GCHQ) is a British intelligence agency that provides signals intelligence to the British government and armed forces. Prior to 1983 its existence was not acknowledged, despite the fact that it openly recruited graduates. Following a spy scandal in 1983, the organisation became known to the public, and the government of Margaret Thatcher decided a year later that employees would not be allowed to join a trade union for national security reasons. The Minister for the Civil Service is a position held "ex officio" by the Prime Minister. This was done through an Order in Council, an exercise of the Royal
Civil Service (United Kingdom) and instructions to departments and agencies regarding the terms and conditions of service of civil servants. It is the guiding document which gives delegation to civil service organisations, from the Minister for the Civil Service, in order for them to make internal personnel policies. The Civil Service Commissioners' Recruitment Code is maintained by the Civil Service Commissioners and is based on the "principle of selection on merit on the basis of fair and open competition." The Osmotherly Rules set out guidance on how civil servants should respond to Parliamentary select committees. A two-volume 125-page "Directory of Civil Service Guidance" was