Cambridge University Spy Ring

Cambridge University Spy Ring


The Cambridge spy ring was a group of British young men recruited as Soviet spies in the 1930s. The group was known in Britain as the Cambridge spy ring, after the University where the men attended classes and were recruited for espionage. In the Soviet Union, the group was known as the "magnificent five." The Cambridge spy ring infiltrated the highest level of the British government, including MI-5, MI-6, the Foreign Office, and the War Ministry. During their career, the group betrayed some of

Kim Philby (right) shown here following the shelling of his vehicle during the Spanish Civil War, was a member of the Communist Party while at Cambridge University, where he recruited and led a ring of spies for the Soviet Union. ©BETTMANN/CORBIS.
Kim Philby (right) shown here following the shelling of his vehicle during the Spanish Civil War, was a member of the Communist Party while at Cambridge University, where he recruited and led a ring of spies for the Soviet Union. ©

Britain's most guarded secrets to the Soviet Union. The group was led by master-spy, Harold "Kim" Philby.

Soviet agents planned to expand their espionage network in Britain as early as 1928. Though several spies operated successfully in Britain at the time the Cambridge ring was founded, Soviet intelligence officials realized that it was necessary to recruit people who had access to the upper echelons of British society, who could land prestigious civil service jobs, to infiltrate the highest levels of British government. To that end, Soviet agents began recruiting young men at Oxford University and Cambridge University into service. They looked for students who held genuine communist or socialist political sympathies, and who possessed the necessary social pedigree to obtain the confidence of high level peers. From Cambridge, Soviet agents persuaded Kim Philby, Guy Burgess, Donald Maclean, Anthony Blunt, and John Carincross into service for the Soviet Union.

Kim Philby. After graduating Cambridge, Kim Philby (1912–1988) failed to land a position in the Foreign Service. He worked briefly at the London Times . Philby proved his worth to Soviet intelligence during this time by smuggling agents and communist supporters out of fascist Austria. He then traveled to Spain as a war correspondent, covering the Spanish Civil War. When World War II began, Philby returned to Britain, finally securing a job with British Intelligence.

From 1944 to 1946, Philby served as director of anti-Soviet counterintelligence for British Intelligence. The position guaranteed his access to top-level British military, intelligence, and government secrets, including World War II battle plans and Cold War agreements between Britain and the United States to thwart the spread of communism is Europe.

In 1949, Philby was stationed in Washington, D.C. as part of an Anglo-American intelligence cooperative operation. For three years, Philby had access to CIA and FBI files. More damaging, he received briefings of Venona Project intercepts, providing him with the ability to inform Moscow of United States efforts to break Soviet communications codes. The Venona intercepts also allowed Philby to monitor American knowledge of Soviet spy networks within the United States, and report defections to Soviet authorities. After returning to London in 1951, Philby continued his career as a mole (double agent) for over a decade.

Guy Burgess. Guy Burgess (1910–1963) worked as a radio correspondent for the BBC from 1936 through 1944. During World War II, Burgess was also employed by British intelligence agency, MI5. Burgess was somewhat successful in transmitting messages to Soviet agents via radio broadcasts and smuggled several key documents to Moscow. Burgess stole some of the most sensitive information in the career of the Cambridge spy ring. While working for MI-5 in London, he smuggled copies of documents relating to nuclear weapons development. He also informed the Soviet government of United States and British plants to create the North Atlantic Treaty Organization (NATO), a European-American military alliance system.

In 1950, Kim Philby requested that Burgess be assigned to the Washington, D.C., bureau of the British Foreign Office. Burgess worked as Philby's assistant until he came under the suspicion of British intelligence. Philby then sent Burgess back to London, presumably to avoid suspicion upon himself.

Donald Maclean. The third member of the Cambridge spy ring, Donald Maclean (1913–1983), worked closely with Burgess. After graduating from Cambridge, Maclean worked in diplomatic service. In 1950, he became head of the Foreign Office's American Department.

While working at the British Embassy in Washington, D.C., Maclean was the main source of information regarding United States and British communications, advising Moscow on Anglo-American policy. In 1951, Maclean was tapped to be the British representative on the American-British-Canadian council on the sharing of atomic secrets. With Burgess, Maclean used his position to funnel highly classified atomic secrets to Soviet military intelligence. The two men did not steal technical information about the atomic bomb, but did provide Moscow with accurate assessments of the American atomic arsenal, production capabilities, and nuclear resources.

The Defections of Maclean, Burgess, and Philby. In 1949, Robert Lamphere, an FBI counterintelligence agent working with the Venona project, discovered that someone was sending telegraph messages from the British Embassy in Washington, D.C. to Moscow. The sender, under the codename "Homer" was later identified as Maclean. Philby, while working in Washington, learned of the FBI investigation of Maclean. Philby then devised a plan to warn Maclean of his impending exposure, while protecting himself and the rest the Cambridge spies.

Philby and Burgess agreed that Burgess would endeavor to be recalled by the Foreign Office to London, where he could arrange to meet with, and warn Maclean without arousing suspicion. Since Burgess had lived in the Philby family home while assigned to his Washington, D.C. post, Philby cautioned Burgess not to attempt to defect to the Soviet Union with Maclean should he decide to escape. Burgess agreed to escort Maclean to safety, but to return to Britain to avoid drawing attention to other members of the Cambridge ring.

Days before he was scheduled to be questioned by British and American intelligence officials, Maclean, with Burgess, escaped to France. Once on the continent, they made their way to Moscow via a network of KGB safe houses. Soviet authorities insisted that Burgess defect with Maclean. Burgess lived in Russia until his death in 1963, though he reportedly did not attempt to further participate in the Soviet government. Maclean learned Russian and spent his remaining years working as an economic analyst and advisor on Western policy.

When British intelligence learned of Burgess and Maclean's defection, and acknowledged their roles in Soviet espionage operations, Philby was immediately placed under suspicion as a possible Soviet mole. In 1955, he deftly weathered MI-5 and MI-6 interrogation. After being released from his job at MI-6, he later was permitted to return to the civil service. Philby continued to act as a mole for Soviet intelligence for several more years, though he had limited access to top-secret materials.

In 1963, under renewed suspicion of espionage, Philby took a position as Foreign Office correspondent in Beirut, Lebanon. Later that year, a Soviet intelligence agent defected to the West. While being interrogated by Australian and British intelligence in Sydney, the defector named Philby as one of the Soviet's greatest human intelligence assets. Philby quickly defected to the Soviet Union, where he spent the rest of his life. He worked with the KGB, training spies for operation in the West. Cambridge spy ring member Anthony Blunt aided Philby's final escape.

Anthony Blunt. Though not the most active spy in the Cambridge ring, Anthony Blunt (1907–1983) aided Soviet agents' recruitment efforts at Cambridge. Blunt supplied the names of possible moles, and regularly attended communist political meetings in search of young recruits.

Blunt received degrees in history and art history from Cambridge. At the outbreak of World War II, Blunt went to work for British Intelligence. Blunt lacked the high-level security clearances possessed by other Cambridge spy ring members, however he was successful in smuggling photographs of documents regarding British troop locations and counterintelligence reports to his KGB contact, Yuri Modin. Blunt also provided information to Soviet military intelligence regarding British code breaking efforts against the Germans. After the war, he cultivated a reputation as a leading national academic. Socially, he often refused to comment on national and international political matters, leading colleagues to believe he had grown disillusioned and possessed little interest in the subject.

Though Blunt did conduct espionage for the Soviets after World War II, a majority of his operations was conducted during wartime. He was the first member of the Cambridge spy ring to retire from service, returning to his career as an art historian and museum curator, and the only member to remain in Britain.

In 1964, an American, Michael Straight, who had attended Cambridge with Blunt told FBI and MI-5 agents that Blunt had tried to recruit him to spy for the Soviet Union. After being exposed as a member of the Cambridge spy ring, Blunt provided MI-5 and MI-6 with some information regarding his past operations and associates, most of whom had by 1964 died or defected to Russia and were out of reach of British prosecutors. In exchange, Blunt was not tried for his offenses. He continued his career in art history, managing the Courtauld Collection until his retirement. His career as a spy for the Soviet Union was exposed to the public by the government officials under Prime Minister Margaret Thatcher in 1979. He was stripped of his knighthood and academic honors. By the time of his exposure, the public was already well acquainted with the stories of agents Maclean, Burgess, and Philby. Blunt was then presumed to be the final member of the infamous Cambridge spy ring.

John Carincross. In 1990, a fifth member of the Cambridge ring was publicly identified. John Carincross (1913–1995) worked with Maclean in the Foreign Office before being transferred to the offices of the Treasury in 1940. Through his connections with British intelligence and the Treasury, Carincross obtained a significant amount of information about the British Cipher School and code-breaking program at Bletchley Park. Heeding Carincross's warnings, Soviet intelligence changed their diplomatic, military, and intelligence codes before the end of World War II. Bletchley Park cryptologists thus, had to begin anew with efforts to break the Soviet code.

Carincross also leaked information about British and American nuclear programs. Analysts estimate that the Soviet Union was able to develop nuclear weapons three years faster, and millions of dollars cheaper, with the aid of intelligence from moles such as the Cambridge spies.

Similar to Blunt, when Carincross was exposed, he provided information about Soviet espionage networks to British intelligence. While the ultimate usefulness of such information remains the subject of debate, he was nonetheless granted some level of immunity from prosecution. When his career as a Soviet spy was made public, he left England for France.

The legacy of the Cambridge University spy ring. The actual damage to British and American national security caused by the activities of the Cambridge spy ring may never be fully assessed. Even with the declassification of reports and archives in the former Soviet Union, a comprehensive account of secrets stolen by the ring remains illusive. The Cambridge spies did have a profound short-term influence on British and American intelligence operations. Both nations stepped up counterespionage efforts to root out similar moles in government agencies. Competitive tensions between MI-5 and MI-6 in Britain, and the CIA and FBI in the United States, were greatly exacerbated after Kim Philby's defection. The agencies blamed each other for not conducting adequate background checks on British personnel sent to work on joint Anglo-American intelligence operations, and for not discovering the Soviet spy network in time to prevent the loss of substantial information. The incident humbled both the British and American intelligence communities, and even fostered mistrust between the two nations. For a decade, Britain and American intelligence forces shared only limited information.

Relations between the British and American intelligence communities gradually became more supportive, eventually returning to the cooperative status enjoyed in the early Cold War years. When the Cold War ended with the fall of the Soviet Union, the extent to which rival nations infiltrated each other's governments with spy networks was made apparent. Declassification of documents relating to Cold War espionage proved the Cambridge spy ring was far from alone in its operations.

The Cambridge ring gained its notoriety not only from its exploits of espionage, but also because of it seemingly unlikely cast of characters—upper class, well-schooled, British citizens who fit well into the "old boys" network that dominated the British civil service. Their social credibility helped them gain access to the nation's top secrets. Further complicating the legacy of the spy ring was the effectiveness with which the group operated. Philby, Burgess, Blunt, Maclean, and Carincross spent years building reputations as loyal British citizens and staunch anti-communists before beginning active espionage during World War II. With the exception of one payment made to Kim Philby when his family was in dire financial need, none of the Cambridge spies demanded compensation for their services to Soviet intelligence. The group thus seemed ideologically loyal to communism, as opposed to performing espionage for personal gain.

Regardless of motive or the ultimate success of their operations, the Cambridge spies are some of the most infamous figures of British intelligence. Subsequent incidences of British citizens in the employ of Soviet intelligence stealing sensitive information from high-level officials further embarrassed British intelligence. In 1963, the Profumo Affair exploded to public attention when intelligence agents and journalists learned that the mistress of a British cabinet minister was a Soviet informant. The "Sex for Secrets" scandal helped bring down the administration of Prime Minister Harold Macmillan. Ironically, Macmillan, while serving as Foreign Secretary, cleared Kim Philby of wrong-doing eight years before his ultimate defection.

Labeled traitors in Britain and America, the "magnificent five" enjoyed fame in the Soviet Union. When Kim Philby died there in 1988, he was buried in Moscow with full state honors.



Boyle, Andrew. The Climate of Treason: Five Who Spied for Russia. London: Hutchinson, 1979.

Brown, Anthony Cave. Treason in the Blood. Boston: Houghton Mifflin, 1994.


Teagarden, Ernest M. "The Cambridge Five: The End of the Cold War Brings Forth Some Views from the Other Side." American Intelligence Journal 18, no. 1/2 (1998): 63–68.


Cold War (1945-1950), The Start of the Atomic Age
Cold War (1950-1972)
KGB (Komitet Gosudarstvennoi Bezopasnosti, USSR Committee of State Security)
MI5 (British Security Service)
MI6 (British Secret Intelligence Service)
OSS (United States Office of Strategic Services)
Soviet Union (USSR), Intelligence and Security
Special Relationship: Technology Sharing Between the Intelligence Agencies of the United States and United Kingdom

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