Question: Where is the base of one of the three main British intelligence agencies?

Related documents: [0]  [DOC] The Government of the United Kingdom maintains intelligence agencies within several different government departments. The agencies are responsible for collecting and producing foreign and domestic intelligence, providing military intelligence, performing espionage and counter-espionage. Their intelligence assessments contribute to the conduct of the foreign relations of the United Kingdom, maintaining the national security of the United Kingdom, military planning and law enforcement in the United Kingdom. The three main agencies are the Secret Intelligence Service (MI6), the Security Service (MI5), and the Government Communications Headquarters (GCHQ). [END] 
[1]  [DOC] The Government Communications Headquarters (GCHQ) is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance to the government and armed forces of the United Kingdom. Based in "The Doughnut" in the suburbs of Cheltenham, GCHQ is the responsibility of the country's Secretary of State for Foreign and Commonwealth Affairs, but it is not a part of the Foreign Office and its director ranks as a Permanent Secretary. [END]  
Answer: Cheltenham
Cheltenham