Owing its origins to Lord Trenchard's desire to establish an elite corps of civilians who would serve their country in flying squadrons during their spare time, the Auxiliary Air Force (AAF) was first formed in October 1924. Today, the Royal Auxiliary Air Force (RAuxAF) is the primary reinforcement capability for the regular RAF. It consists of paid volunteers who, at weekends, evenings and holidays, train to support the RAF, particularly in times of national emergency and conflict. This has seen the AAF play important roles in the Battle of Britain, its squadrons claiming 30 per cent of enemy 'kills'. Other notable achievements by AAF pilots include the first German aircraft destroyed over the British mainland and its territorial waters, the first U-boat to be destroyed with the aid of airborne radar, the first destruction of a V-1 flying bomb, and an AAF squadron claimed the highest score of any British night fighter squadron. It was an AAF squadron which was the first to be equipped with jet-powered aircraft. Receiving 'Royal' status in 1947 in recognition of its contribution to victory in the Second World War, the RAuxAF also came to the fore during the Cold War providing home defense as the regular squadrons were shipped to hotspots around the world. In more recent times, squadrons and personnel of the RAuxAF have seen action in Iraq and Afghanistan This book presents, for the first time, the history and development of all the squadrons and units that made up the Auxiliary and the Royal Auxiliary Air Force, including the Balloon Squadrons, the Maritime Headquarters Units, Fighter Control and Radar Reporting Units, Royal Auxiliary Air Force Regiments and of course the Women's Auxiliary Air Force. These devoted warriors continue to serve alongside the regular forces in defense of the United Kingdom, ready to be called into action whenever their country is in time of need.