Michael Foot was falsely exposed as a Soviet spy"
I thought that accusation was made against Wilson,
Harold Wilson conspiracy theories
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Harold Wilson in 1974

Since the mid-1970s, a variety of conspiracy theories have emerged centring on British Labour Prime Minister Harold Wilson who served as the Prime Minister of the United Kingdom from 1964 to 1970 and 1974 to 1976, winning four general elections. These range from Wilson having been a Soviet agent (a claim which MI5 investigated and found to be false), to Wilson being the victim of treasonous plots by conservative-leaning elements in MI5 - the latter being claims which Wilson himself made.