Cipher Vehicles, Decoding Messages, and War Devastation

The work of GCHQ started just after the end of World War One as telegraph became a vital means of military communications. We hear from people who worked at the listening station in the Yorkshire seaside resort of Scarborough during World War Two and the Cold War. BBC security correspondent Gordon Corera reveals how Government Communications Headquarters – GCHQ - has been listening in for 100 years.