When Prime Minister Chamberlain’s ultimatum to Germany expired on 3 September 1939, World War II found the home-based Royal Air Force established with a strength of: 55 Bomber Squadrons with Bristol Blenheim IVs Vickers Wellington Is and IAs Armstrong Whitworth Whitley IIIs and IVs Handley Page Hampdens 35 fighter squadrons with   Hawker Hurricanes Supermarine…