Where is the base of one of the three main British intelligence agencies?
British intelligence agencies:  The three main agencies are the Secret Intelligence Service (MI6), the Security Service (MI5), and the Government Communications Headquarters (GCHQ). Government Communications Headquarters:  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.
i don't know