A government booklet warning prominent Britons to be on their guard against Russian spies is being made available to the public for the first time in over 40 years.
Their Trade Is Treachery was published by the Central Office of Information in 1964.
The advice came after the resignation of Secretary of State for War John Profumo following a relationship with Christine Keeler, who was also linked to Yevgeny Ivanov, a senior naval attache at the Soviet embassy in London.
The scandal prompted concerns about the risk of sensitive information being passed to Russia. The leaflet warned enemy intelligence services would exploit a person's weaknesses and use “unashamed” blackmail against their target.
“On the whole, guile, patience, and enticement are employed by enemy Intelligence Services operating in Britain when recruiting agents,” the book said.
Their Trade Is Treachery is published by Beautiful Books on June 18, priced at £8.99.