Sir Roger Hollis (1905–1973) joined the Service in 1938 following an earlier career as a businessman in the Far East. During the Second World War, he was ahead of many of his counterparts in foreseeing the post-war threat from Soviet espionage and Communist subversion, issues that were to be of major concern by the time he entered the senior ranks of the Service.

He was appointed Deputy Director General in 1953 and Director General in 1956, serving in that capacity for nine years. He retired from the Service in December 1965.

In 1981, allegations were published claiming that Sir Roger had been a Soviet secret agent. These were investigated and found to be groundless.