Why was the Cambridge Five scandal so embarrasing to MI5? And how significant was Oleg Lyalin's success in restoring faith in British Intelligence? Tristan Donovan discusses the notorious spy-ring and its lasting impact with Andrew Lownie, the author of Stalin's Englishman.See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.