Gordon Corera becomes the first journalist allowed to record inside GCHQ's listening station at Bude on Britain’s south-west coast. The station has spied on global communications satellites for decades, sucking in signals from space. He takes us from the Cold War, when GCHQ was quietly eavesdropping on the front lines in Berlin, to the current digital era. And Gordon finds out how, following the revelations of Edward Snowden, the agency has been forced out into the open.