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

Context paragraphs:
Defence Strategic Policy and Intelligence Group: The Defence Strategic Policy and Intelligence Group (SP&I) of the Australian Government Department of Defence is responsible for defence diplomacy, strategic policy, international security, and military intelligence coordination and advice to the Prime Minister of Australia, Minister for Defence, Secretary of the Department of Defence, and Chief of the Defence Force.  The Defence Strategic Policy and Intelligence Group is led by the Deputy Secretary for Strategic Policy and Intelligence and comprises four policy divisions and three intelligence agencies, which are the Australian Defence Organisation members of the Australian Intelligence Community.

British intelligence agencies: 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).

Gustav Laabs: Gustav Laabs (born 20 December 1902-died 12 March 1980) was a German SS commander during the Nazi era.  During the Second World War, he worked as a gas van operator at the Chełmno extermination camp in Wartheland.  As an operator of a gas van, Laabs was directly involved in and responsible for the genocidal extermination of over 100,000 men, women and children, most of whom were killed on account of being Jewish.  After the war, he was tried and convicted for his crimes against humanity.  Despite being convicted, Laabs was given the lenient sentence of 15 years (subsequently reduced to 13 years) by a regional court in Landgericht Bonn, Germany.  Far from being outliers, such instances of leniency, extended to perpetrators of genocide and crimes against humanity during trials in post-Nazi Germany, constituted the norm, as evidenced by the fact that most of the perpetrators of Nazi war crimes and the Final Solution were not brought to justice.  Many former SS officers and Nazis, who were directly responsible for perpetrating genocide and murdering countless innocent people, were contracted to work for US and British intelligence agencies as part of the war against the USSR and Communism (also see Operation Paperclip for more on post-WWII Allied collaboration with Nazis).

Alliance Base: Alliance Base was the cover name for a secret Western Counterterrorist Intelligence Center (CTIC) that existed between 2002 and 2009 in Paris.  The existence of CTICs were first revealed by Dana Priest in a November 17, 2005 "Washington Post" article, while she referred to the Alliance Base in a July 2, 2005, article.  The name was chosen in reference of Al Qaeda, which means "The Base" in Arabic.  It was headed by a French General assigned to the Directorate-General for External Security (DGSE), and largely funded by the CIA's Counterterrorist Center.  It hosted officers from Great Britain, France, Germany, Canada, Australia and the United States and was used for intelligence exchange and operational planning.  Its existence was confirmed on 8 September 2006 by Christophe Chaboud, chief of the UCLAT (""Unité de Coordination de la Lutte contre le Terrorisme"", "Fight against Terrorism Coordination Unit"), in an interview to RFI.  Although intelligence exchange between intelligence agencies has become more and more widespread in the last decade, in particular following the September 11, 2001 attacks, this organisation also engaged in operations.

Yulin Naval Base: Yulin Naval Base () is a naval base for nuclear submarines along the southern coast of Hainan Island, People's Republic of China.  This underground base has been reported by several intelligence agencies, especially Indian agencies.  The images collected by the Federation of American Scientists (FAS) in February 2008 shows that China constructed a large scale underground base for its naval forces.

Ardeshir Reporter: Sir Ardeshir Reporter was born in a Zoroastrian Parsee family in Bombay on August 22, 1865.  He was a secret British Intelligence agent in Iran for many years.  In fact, he lived and worked in Iran as a secret British Intelligence agent since 1893.  He came to Iran under the cover of Times' reporter.  It was he who introduced General Ironside to Reza Khan, and it was Ironside who encouraged Reza Khan to seize power.  According to his own will, he was the one, who discovered Reza Khan and guided him in the coup on February 22, 1921.  Therefore he was instrumental in Reza Khan’s 1921 military coup and the consequent establishment of the Pahlavi dynasty and enthronement of Reza Shah in Iran in 1925.  Ardeshir Reporter died in Tehran in 1933.  His son, Shapoor Reporter, was also a secret agent of the British Intelligence Service in Iran who served the Pahlavi family after Reza Shah's death.

Australian Secret Intelligence Service: The Australian Secret Intelligence Service (ASIS; ) is Australia's foreign intelligence agency.  ASIS was formed in 1952, but its existence remained secret even within the Government until 1972.  ASIS is part of the Australian Intelligence Community responsible for the collection of foreign intelligence, including both counter-intelligence and liaising with the intelligence agencies of other countries.  In these roles, ASIS is comparable to the British Secret Intelligence Service (MI6) and the American Central Intelligence Agency (CIA).

Defense Intelligence Agency in popular culture: The Defense Intelligence Agency (DIA) is a military espionage organization of the United States and one of the country's national-level intelligence agencies under the jurisdiction of the U.S. Department of Defense (DoD).  Less known than its non-DoD equivalent or its cryptologic counterpart, the DIA and its personnel have at times been portrayed in works of American popular culture.  As with other U.S. foreign intelligence organizations, the agency's role has occasionally been confused with those of law enforcement agencies.

Government Communications Headquarters: 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.

Israel's Secret Wars: It explores the role of secret intelligence and covert activities in the Zionist movement before independence and explore the operational and political histories all three major Israeli intelligence agencies Aman (military intelligence), Mossad (foreign intelligence and covert operations) and Shin Bet (internal security).

Supporting paragraphs: British intelligence agencies Government Communications Headquarters
Answer: Cheltenham