I can strongly recommend the book "The Spy and the Traitor" about Oleg Gordievsky and MI6: https://www.penguin.co.uk/books/279/279582/the-spy-and-the-traitor/9

I can strongly recommend the book "The Spy and the Traitor" about Oleg Gordievsky and MI6: https://www.penguin.co.uk/books/279/279582/the-spy-and-the-traitor/9780241186657.html https://www.penguin.co.uk/books/279/279582/the-spy-and-the-t... It goes into quite a lot of detail about what it was like to work in the KGB at that time.