After the war he became a businessman selling electrical equipment. As he often travelled to Eastern Europe he was asked to join MI6. In 1959 he played an important role in helping a Russian intelligence officer, Major Kuznov, to defect to the West.
In 1961, Oleg Penkovsky, deputy head of the foreign department of the Coordination of Scientific Research, told a British diplomat that he wished to sell Soviet secrets. Wynne was chosen as Penkovsky's British contact. In April 1961 Penkovsky began passing information about Soviet missile developments, nuclear plans, locations of military headquarters and the identities of KGB officers. This included evidence that Nikita Khrushchev had been making false claims about the number of nuclear missiles in the Soviet Union. Over a period of 14 months Penkovsky passed photographs of 5,000 secret papers to the CIA and MI6.
Penkovsky, described by one intelligence officer as the "best spy in history", was considered so important that a meeting was arranged between him and Sir Dick White, head of MI6.
The Soviet Union had two double agents, William Whalen and Jack Dunlap, working in Washington. Eventually information was passed to the KGB that Penkovsky was spying for the West. On 20th October, 1962, Russian intelligence officers raided Penkovsky's apartment and discovered a Minnox camera that had been used to photograph secret documents.
Penkovsky was immediately arrested and it was not long before he gave the name of Wynne as his British contact. A few days later Wynne was arrested at a trade fair in Budapest, Hungary, and flown to the Soviet Union.
After being convicted Wynne was sentenced to eight years' imprisonment and Oleg Penkovsky was sentenced to death and was executed on 16th May 1963.