For the first time, the BBC has given detailed access to the plans it drew up in the Cold War for a Wartime Broadcasting System to operate in the event of nuclear war. Paul Reynolds, a former BBC diplomatic and foreign correspondent, has been studying the secrets of what was known as the "War Book".

The War Book reveals a world of meticulous BBC planning. The Wartime Broadcasting System (WTBS) - referred to in the book as "Deferred Facilities" - would have operated from 11 protected bunkers spread across the UK.