The party, arranged by the KGB, had been a classic "honeytrap". The Soviets used the photographs to blackmail Vassall into working for them as a spy, initially in the Moscow embassy, and later in London, following his return there in June 1956. He returned to the Admiralty, where he worked first in the Naval Intelligence Division, and then, as the clerical officer assistant to the Private Secretary, in the Private Office of Tam Galbraith, a Conservative Party politician and Civil Lord of the Admiralty. At the time of his arrest he was working in Military Branch II. During his espionage career, Vassall provided the Soviets with several thousand classified documents, including information on British radar, torpedoes, and anti-submarine equipment. His obituary-writer in "The Times" commented that "Vassall was never more than a low-level functionary, but there was nothing low-level about the damage he was able to inflict". Similarly, Chapman Pincher regarded Vassall as "the classic example of the spy who, while of lowly rank, can inflict enormous damage because of the excellence of his access to secret information". Pincher continued: "I am in no doubt that the recruitment and running of Vassall was a major triumph for the K.G.B. He provided information of the highest value to the Soviet defence chiefs in their successful drive to expand and modernise the Red Navy."