David Clarke. How UFOs Conquered the World: The History of a Modern Myth. London: Aurum Press, 2015. Clarke is a journalist and academic who has also worked with the National Archives on the declassification of Britain's official UFO files. Here he takes a wider view, providing a social history of ufology (a subject he has already tackled, with Andy Roberts) framed through his own personal journey from believer to sceptic. Given that, I'm a bit disappointed that there seems to be little about phantom airships, a topic which he pioneered. Still, there's plenty of interest here.
Robin Prior. When Britain Saved the West: The Story of 1940. New Haven and London: Yale University Press, 2015. Or, to be slightly more precise, when Britain saved the West by saving itself - Dunkirk, the Battle of Britain, and the Blitz (and Churchill rather than Chamberlain or indeed Halifax). Knowing Prior's previous work (mostly on battles of the First World War), this will be thoroughly researched and logically argued. At first glance, it's not clear that he is challenging much of the historiographical consensus on 1940, however: for example he allows that Fighter Command had the Battle of Britain well under control, while making the point that this wasn't obvious to contemporaries. Which is to say that Prior is sensible. As Prior says there aren't many military histories of 1940 as a whole, so a fresh, integrated and scholarly account is welcome.
Nigel Watson. UFOs of the First World War: Phantom Airships, Balloons, Aircraft and Other Mysterious Aerial Phenomena. Stroud: History Press, 2015. With Clarke, a sometime-collaborator, Watson is the other major pioneer of the history of phantom airships (and who also is more interested in their cultural significance than the remote possibility of physical reality). The collection which he edited, The Scareship Mystery (2000), has long been my standard reference on the subject for both peacetime and wartime mystery aircraft scares -- not that there are many competitors, mind. This is something of an update, a bit less in-depth but also broader. In fact, apart from the more usual mystery aircraft wave of the period, there is a chapter on the Australian mystery aeroplane panic in 1918 drawing upon my own research, which is very gratifying. There is also some information on Norwegian mystery aircraft scares, in 1908 and during the First World War, which I don't know much about. A chapter on wartime spy scares and other rumours bears on my own research in this area.