It’s 1940. And the world’s first real air battle is being fought in the skies of the UK. This is the Battle of Britain, in which the Royal Air Force would triumphantly fight off the threat of the German Luftwaffe. Behind the brave pilots and pioneering technology lies an often-forgotten secret weapon. A system, developed by the RAF at Bentley Priory in North London. It was called the Dowding System, a system that would deliver victory. To find out more about the Dowding System and its critical role in the Battle of Britain’s outcome Dan Snow visits Bentley Priory to meet Battle of Britain historian Stephen Bungay.