The Cambridge Spy Ring: its creation, significance, and effects on Britain and the West

Ian Yeung
discusses the importance and legacy of this well-known group.
  In 1934, three students at Cambridge University were recruited by the KGB (the intelligence service of the USSR) to become spies. Over the next few years, two more joined their group. At the time, this group of five young students was relatively unimportant and had no name. However they have since become known as the “Cambridge Spy Ring”, arguably the greatest spy ring the West had ever seen. The reason for their infamy was because of their very success in penetrating deep into an important western political establishment, namely the British Intelligence Services.

The initial group of undergraduates consisted of Guy Burgess, Donald Maclean, and Harold “Kim” Philby. Guy Burgess was having a homosexual relationship at that time with another fellow Cambridge alumnus Anthony Blunt, who was later recruited in 1937 along with John Cairncross. This was the central group of five. Additional KGB spies recruited at Cambridge were Leo Long, Michael Witney Straight, Dennis Proctor and Alister Watson (although he never confessed) but these men were relatively independent and thus were not really members of the Cambridge Spy Ring as such. All the members of the central five including Leo Long were undergraduates at Trinity College, Cambridge except Donald Maclean who was at Trinity Hall.

At the pinnacle of the Ring’s power and importance, all the members were in extremely influential positions. Long worked for British Military Intelligence during the war and tried to join MI5 (the British organization in charge of counter-espionage) but failed to do so. Watson worked for the Radar and Signals Establishment of the Navy before becoming head of the Submarine Detection Research Station at the Admiralty Research Laboratories where he had access to many secrets but was subsequently transferred to a less sensitive post when MI5 discovered his Marxist leanings. Proctor was Permanent Secretary at the Ministry of Fuel and Power by 1965 and previously had been Stanley Baldwin’s private secretary. Straight was an American who was later discovered by the FBI (the American counterespionage and domestic security agency) and provided one of the first leads for the security services in uncovering the spy ring.

Cairncross had worked for the Treasury and during the war for the Government Code and Cipher School (GC&CS; the forerunner of GCHQ, which is the Government Communications Headquarters for intelligence gathering by electronic means). The pinnacle of his career however was when he was secretary to Lord Hankey, Minister without Portfolio in Churchill’s war cabinet. Here he was able to pass over information relating to the development of atomic bombs (arguably the most important information from a tactical and strategic perspective during the 1940s). He was also part of MI6 (the British organization dealing with intelligence about foreign nations) for a time.

Maclean was Head of the American Department in the Foreign Office. Thus he was able to betray to the Soviets all policy and discussions between the British and the Americans along with all the codes and ciphers he had access to. For example, he betrayed many of the messages between Roosevelt and Churchill during the war. Additionally, he had access to highly classified information on Nuclear Weapons Development. In his book, Yuri Modin (the last KGB controller of the spy ring) described Maclean’s political intelligence as being “valuable”.

Burgess was also a member of the Foreign Office and was Second Secretary under Philby in Washington. He had also worked for MI5. Yuri Modin described Burgess as “the real leader of the group”.

Blunt also worked for MI5 during the war but left to become the Director of the Courtauld Institute in London and later became the surveyor of the Queen’s pictures. Blunt admits that he left MI5 because “I needed my art”. The reason the Soviets did not resist this was because they had the intelligence services thoroughly penetrated with the “Third Man” of the spy ring: Kim Philby.

Kim Philby was brilliant. Modin describes him as “the greatest spy of the century”. Philby’s career in intelligence began in the summer of 1940 when he joined the Special Operations Executive (SOE). The SOE was a wartime organization, which was responsible for carrying out covert operations against the Nazis in Occupied Europe (eg. working with the French Resistance). Philby then joined the Secret Intelligence Service (aka MI6) in 1941. He rose quickly within the organization and in the summer of 1944 executed the “master stroke of Communist subversion” as described by Anthony Glees in his book on the matter. Philby became the head of Section IX in MI6. Section IX dealt with counter-espionage efforts against the Soviets. This is a masterstroke by the KGB because from then on, any effort by the British to catch Soviet spies would be fruitless. Philby would discover about any such attempt and use his influence and considerable power to spoil such an attempt. Additionally he would be able to warn his Soviet controllers and thus they could take appropriate action.

Even more damaging, Philby (and to a lesser extent the others in the spy ring who were also working within the intelligence services) knew the identity of almost every British (and probably most American) spies in the Soviet Union. The KGB could then either eliminate the spies (which would throw suspicion on Philby) or even more cunningly begin to feed these spies with false information. As Philby knew the identity of so many spies and British intelligence was so thoroughly penetrated by the Soviets, the KGB would be able to confuse MI5 and MI6 to such an extent that they would effectively become severely paralyzed. They would then be forced to spend valuable resources in an attempt to follow every lead and thus never be able to find the real spies. To compound the problem during the 1950s, according to Peter Wright’s book, KGB officers and spies were outnumbering MI5 officers by more than three to one. Faced with such odds and obstacles it is not surprising that MI5 seemed to be rarely successful during the 1950s and 1960s. Additionally much of MI5’s tradecraft was compromised. Blunt betrayed the use of special microphones (called special facilities) to the KGB and thus for many years MI5 was unable to successfully and optimally bug many sites (eg. The Communist Party of Great Britain’s headquarters).

Philby was a successful spy because he possessed the qualities needed. He was highly intelligent and hard working. In fact, all the members of the spy ring were highly intelligent; Cairncross had come first in the Foreign Office entrance exam. Philby was also facile and at times an excellent actor. But his hallmark was his charm. Although he had a slight stutter, he became immensely popular in MI6 and acquired many friends and contacts in MI5, MI6, and the Central Intelligence Agency (CIA; the American intelligence service directed against foreign powers). Philby in fact trained the future CIA head of counter-intelligence, James Jesus Angleton, and was friendly with him. Proof of his incredible social skills was the fact that he was able to maintain a reasonable façade of innocence from 1951, when Burgess and Maclean were forced to defect to the USSR, till 1963 when he himself had to defect from Beirut as his arrest became imminent. However the ultimate evidence of his unparalleled charm as a spy was on November 7th 1955, when the Foreign Secretary and future Prime Minister, Harold Macmillan publicly cleared Kim Philby of all suspicion of being the “Third Man” in the Cambridge Spy Ring in public, in the House Of Commons.

The Cambridge Spy Ring was very close. All five members knew each other and also knew each other’s hidden secrets. One point to note is that from an operational perspective, it was myopic to have each man know the full membership of the spy ring, as the investigation of one could have rapidly revealed the other members of the group. In fact that was mostly how the spy ring became unravelled in the end. But the creation of this group of idealistic young Cambridge students was a unique by-product of the political climate of the time.

In the 1930s, Fascism was on the rise. Hitler was appointed Chancellor of Germany in 1933. Many saw Fascism as a threat to the liberal democracies of Europe including that of Britain. Additionally, Marxism had become quite popular among many intellectuals especially those in Oxbridge. Blunt himself confessed that “when I returned to Cambridge from London, everyone had become Marxists”. The Cambridge Spy Ring saw Marxism as the way forward and also the way that Europe could be defended from the likes of Hitler and Mussolini.

In 1941, Hitler launched Operation Barbarrossa. This was the codename for his plan to attack and conquer the USSR. In doing so, he broke the Treaty of Non-Aggression between the two countries and pushed the USSR onto the same side as the UK. Thus from 1942 onwards, the UK and the USSR were allies and agreed to cooperate fully on all fronts. The UK did so completely and honestly. The USSR however did not and took advantage of the opportunity to plant various spies in the Establishment (the upper echelons of British society and government) which could serve Soviet post-war plans. These plans were the setup of worldwide revolution (as ordered by Lenin) and more importantly the setup of a communist Eastern Europe. There are several reasons why the alliance made Soviet espionage on Britain easier.

Firstly, both countries were now pursuing the same goal, which was the defeat of Nazi Germany.  This allowed for the easier recruitment of spies.  Also this meant that for the spies in Cambridge, they could continue their activities in the belief that they were not committing treason as they were allied to the Soviets now.  Thus they could assuage any doubts they had from their conscience if they possessed any about their activities.  Additionally, this may have made them more committed as they now clearly saw that what they were doing was benefiting both sides.  Blunt said that he himself felt that “we weren’t doing enough for the Soviets and thus felt his role was crucial as it helped them further”.  

One example of the spies helping the Soviets during the war is John Cairncross leaking Ultra information.  Ultra was the codename given to intelligence derived at Bletchley Park by GC&CS.  Using primitive computers, Bletchley Park was able to decrypt many German encrypted messages including those of the highest importance, which were encrypted by the vaunted German Enigma machines.  Cairncross was working at GC&CS during the war and was able to leak many Ultra reports to the Soviets.  It was one of these reports that allowed the Soviets to win the Battle of Kursk, which was a turning point in the war.

The second reason why the wartime alliance aided Soviet intelligence efforts was the order by the then Prime Minister, Winston Churchill to stop further attempts in deciphering and reading Soviet encrypted messages.  True to the spirit of the alliance, Churchill thought it would be wrong to continue the Venona project against the Soviets.  The Venona project was the most guarded intelligence secret by western intelligence services during the Cold War.  It was an effort to systematically read and decipher the “one-time pads” encryption systems used by spies and embassies by most countries of the time.  It was believed that “one-time pads” were the most secure form of encryption possible because they were used only once.  However a breakthrough by a mathematician in the National Security Agency in America allowed Western Intelligence agencies to read much of the Soviet one-time pads compromising Soviet communications.  As described in Peter Wright’s book, compromised communications are one method by which spies can be caught.  Thus the decision by Churchill to cease further efforts to decipher Soviet communications made the detection of the Cambridge Spy Ring by MI5 much more difficult. 

However there is another explanation of why the decision was taken on June 22nd 1941, to cease Venona work against the Soviets.  Both Philby and Blunt occasionally sat on the Joint Intelligence Committee (JIC).  The JIC was a committee with members from MI5, MI6 and other British intelligence services.  It’s therefore possible that Blunt and Philby somehow influenced the decision that eventually made detection of them and their fellow spies more difficult.  This introduces a new concept.  That the Cambridge Spy Ring were not spies, but rather moles.  The definition of a spy is a person who reports information back to the organization running him or her.  A mole is far more insidious individual because additionally he/she can directly influence decisions and policy themselves.  Thus because of the importance and high status of the Cambridge Spy Ring members within the government and the British intelligence services, the Soviets were able to directly manipulate the British government to a certain extent.  This is one reason why the group was so damaging to this country’s interests and has fascinated many scholars ever since. 

Worst still, one should remember that Foreign Policy is formulated with information derived from intelligence sources.  If those intelligence sources are compromised, those polices are thus not optimally effective.  This means that while the Cambridge Spy Ring was operational, Britain was severely hampered on the world stage in its interactions with the USSR. 

One reason for the disproportionate amount of influence wielded by the five members of the Cambridge Spy Ring can be explained by the British social structure of the 1940s and 1950s.  At that time, the country was ruled by small elite section of society known as the “Establishment”.  Being firmly rooted in it, thus the Cambridge Spy Ring members had a great deal of power.  Additionally, a unique trait of English society at that time helped the Cambridge Spy Ring members as well.  These were the formal and informal networks that existed at the top.  Formal networks were the strict hierarchical links that the members of the Ring had with their respective organizations.  Informal networks were the links that the spies had to other important people in Whitehall via school and university friendships for example.  An example of this is the Apostles Society.  This was an elite secret Cambridge society for left wing intellectuals, which at the time also comprised a substantial homosexual membership.  Many of the Cambridge Spy Ring were members of this and maintained their contacts with fellow members.  As homosexuality was illegal in the 1930s, those in the society were extremely loyal to one another to avoid their undergraduate activities being exposed.  This is one reason why MI5 were loathe to investigate the Cambridge Spy Ring fully as many of their friends and contacts were important public figures now and thus potentially embarrassing to investigate.  Subversion by of these important public figures by members of the Spy Ring via informal networks is extremely hard to study as few records exist of party conversations for example.  Thus confessions are needed from the Cambridge Spy Ring members themselves if the full truth is ever to be known.   As all the members of the Cambridge Spy Ring are now deceased, it is unlikely that this will ever occur.

The effects of the Cambridge Spy Ring on Britain and the West are vast.  The first major effect was on Whitehall and public morale after the 1951 defection of Burgess and Maclean to the Soviet Union.  The very concept that intelligent, well-brought-up sons of England could betray the country frightened and horrified the nation.  In MI5, it brought to the surface deep fears among the senior officers of penetration and MI5 became intensely introspective and paranoid for many years to come.  One by-product of this witch-hunt for suspected moles within the intelligence services was that it ruined the careers of many decent and able-bodied individuals. 

The second implication was the exaggeration of the existing antipathy between MI5 and MI6.  MI5 felt that MI6 could not be trusted due to Philby’s presence there and MI6 felt that MI5 had been meddling in MI6 business all along.  This was counter-productive for the country as only through full cooperation between all branches of the intelligence services, can foreign agent provocateurs be effectively apprehended in Britain and valuable intelligence material gleaned about Britain’s neighbours on the world stage.  Intriguingly this theme of co-operation between intelligence agencies within Britain and with other NATO countries (especially those of the USA) is especially relevant in today’s modern world as the West seeks to find extreme Islamic fundamentalists across the world and to win the “global war on terror”.   

Anglo-American relations were sorely affected as well. J Edgar Hoover, who was Head of the FBI from 1924 till 1972, was notoriously anti-British.  The existence of the Cambridge Spy Ring and thus Soviet penetration of the British intelligence community merely confirmed his own self held beliefs.  This led to further mistrust by the FBI of its British cousins well into the later half of the 20th century.  A similar effect occurred with the CIA.  Negotiations were also affected.  At the time, the British were negotiating with the Americans for full access to the nuclear research being done by America.  However the Americans were highly reluctant to divulge such secrets as again they perceived the British as being insecure, which was arguably true.

Furthermore, the Cambridge Spy Ring was responsible for the post-war Soviet domination of Yugoslavia and other Eastern European countries.  By suppressing intelligence information about resistance movements in Eastern Europe to Whitehall, those resistance movements came to rely on Soviet help and thus made Soviet domination of those countries after World War II that much easier. 

Finally, the Ring helped bring down the Macmillan government.  It was a succession of security scandals including the Burgess and Maclean defections and culminating in the Profumo affair, which finally forced Harold Macmillan to resign in 1963. Similarly, the Thatcher government came close to ruin, with the publication of various books about the Cambridge Spy Ring and other intelligence matters in the early 1980s along with the public naming of Sir Anthony Blunt’s traitorous affairs in 1979.  However Margaret Thatcher enjoyed a strong majority in Parliament and was thus was able to weather the storm. 

Therefore to summarize, the Cambridge Spy Ring was arguably the finest and most thorough penetration of any country’s government in living memory.  It remains such a supreme and elegant example of an intelligence operation that it must surely be compulsory reading for intelligence services and historians worldwide.  However it would be wrong for Oxford University aficionados and fans, to foolishly believe that Oxford did not produce its own share of traitors during this time period.  An Oxford Spy Ring did exist at the same time.  Members included Phoebe Pool (a courier for the Oxford Ring and a colleague of Blunt’s at the Courtauld Institute), Peter Floud (Director of the Victoria and Albert Museum), Bernard Floud (a senior Labour MP), Jenifer Hart (who joined the Civil Service and married an MI5 officer), Sir Andrew Cohen (a senior diplomat), and Arthur Wynn (who was active in trade union circles and joined the Civil Service).  The Oxford Ring was investigated by MI5 in the 1960s but when many of its members began committing suicide to avoid capture, MI5 decided that public knowledge of such things would be undesirable and so ceased all investigations.  However the Oxford Ring never amounted to much and was never able to cause the same level of damage.  This was due to the Cambridge Ring’s penetration of more vital institutions such as British Intelligence compared to the Oxford Ring.  Thus to conclude once could say that Cambridge remains superior to Oxford even when it comes to treason. 


Ian Yeung is a junior doctor at Southampton University Hospitals NHS Trust.  But he was previously a student at Trinity College, Oxford University.  This essay is a previous winner of the Trinity College Douglas Sladen Essay Prize.