What If? - The Battle of Britain
Historian John Hughes-Wilson looks at what Germany's plans were for the invasion of Britain and asks how Hitler's Operation Sea Lion would have progressed if RAF Fighter Command had been defeated by the Luftwaffe.
He talks to British and German pilots who took part in the battle and visits sites along the GHQ Line, a secret maze of defences in south-east England that would have been activated immediately if the worst had happened.
