The Government Communications Headquarters ( GCHQ ) is a British intelligence agency that provides signals intelligence ( SIGINT ) and information assurance to the UK government and armed forces , under the guidance of the Joint Intelligence Committee . The Government Communications Headquarters ( GCHQ ) is a British intelligence agency responsible for providing signals intelligence ( SIGINT ) and information assurance to the UK government and armed forces . Based in Cheltenham , it operates under the guidance of the Joint Intelligence Committee .