Wright was convinced that the KGB was infiltrating British institutions; among the theories he looked into was the idea that the Labour leader Hugh Gaitskell had been killed by the KGB, a notion put forward by CIA chief of counter-intelligence James Jesus Angleton. With like-minded MI5 officers, Wright became convinced that senior figures in the intelligence world, in politics, and in the trade unions were Soviet agents. After Kim Philby's defection in 1963 following a tip-off, Wright became convinced that the KGB had penetrated the higher reaches of the intelligence agencies. In 1964 he became chairman of a joint MI5/MI6 committee, codenamed Fluency, appointed to find the traitor and investigate the whole history of Soviet penetration of Britain. As claimed in
Spycatcher, Wright believed that Roger Hollis was the highest traitor in MI5. However, operation Fluency involved others not necessarily given to this view, and began to systematically examine evidence.
According to Wright, his suspicions were first raised by Hollis' seeming obstruction of any attempt to investigate information from several defectors that there was a mole in MI5, but he then discovered that Hollis had concealed relationships with a number of suspicious persons, including:
- a longstanding friendship with Claud Cockburn, a communist journalist who was at the time suspected of ties to Soviet intelligence; and,
- an acquaintance with Agnes Smedley whilst Hollis was in Shanghai, at a time when Smedley was in a relationship with Richard Sorge, a proven Soviet spymaster.
Later during his investigations, he looked into the debriefings of a Soviet defector Igor Gouzenko, and found to his surprise that the revelations of that debriefing were not reported or recorded. After a lengthy check, he discovered that it had been Hollis who was sent to Canada to interview Gouzenko. Gouzenko had provided Hollis with clear information about Alan Nunn May's meetings with his handlers. Gouzenko also noted that the man who met him seemed to be in disguise, not interested in his revelations and discouraged him from further disclosures. Gouzenko had not known about Klaus Fuchs, but he had named a low level suspected GRU agent, Israel Halperin, a mathematician, who was later completely cleared. When the Royal Canadian Mounted Police searched Halperin's lodgings, they found Fuchs' name in his address book. Fuchs immediately broke off contact with his handler, Harry Gold, and shortly afterward took a long vacation to Mexico. Wright alleges in
Spycatcher that Gouzenko himself deduced later that his interviewer might have been a Soviet double agent and was probably afraid that he might recognise him from case photos that Gouzenko might have seen in KGB or GRU files, which would explain why Hollis was disguised.
The 'FLUENCY' committee, which examined Hollis' record of service in great detail, unanimously concluded that Hollis was the best fit for the Soviet spy allegations; however, Hollis had retired in late 1965 as MI5 Director-General, by the time the committee finished its report.
A retired civil servant, Burke Trend, later Lord Trend, was brought in during the early 1970s to review the Hollis case. Trend studied the case for a year, and concluded that the evidence was inconclusive for either convicting or clearing Hollis; this was announced by Prime Minister Margaret Thatcher in 1983.
Wright's sights were also focused on Labour prime minister Harold Wilson, whom he suspected to be a Soviet agent. The ‘Wilson plot’ resulted in an investigation into Wilson's background by MI5. This, however, did not result in any conclusive evidence. When Wright retired in 1976, Harold Wilson was again prime minister.
The primary case around which Spycatcher is based, that the Director General of MI5 - Roger Hollis - was a Russian spy, is brought up-to-date by Chapman, Pincher (2009). Treachery: Betrayals, Blunders, and Cover-ups: Six Decades of Espionage Against America and Great Britain. New York: Random House. ISBN 978-1-4000-6807-4.