Russian Spies in the US - Russia's Most Valuable Spy

Klaus Perin was the source of information on America's nuclear programme. He had been working for m i five, a British intelligence agency. When he decided to leave his post in london and join up with communists in U.S., british officials bungled their attempt to stop him. The bomb is now available online as an audio podcast - you can subscribe by emailing jennifer.smith@mailonline.co.uk or call 0203 615 4157.