Dr Mike Osborne's interest in fortification began with childhood visits to castles. It has developed over the years to include all aspects of the topic from Iron-Age forts to Cold War bunkers. He was a volunteer-coordinator for the Defence of Britain Project recording the military structures of the twentieth-century. After a thirty-year-career in education he took early retirement and since then has produced nearly twenty books. Topics include: Civil War sieges and fortifications, drill halls, twentieth-century military structures, a series of county surveys of defences and the best-selling 'Defending Britain'.