Above is a pair of stereo photos kindly sent to me by Tim Lees, who found them in his father's collection. There's a slight mystery as to the occasion. The label at the top reads 'Hendon - July '28', which suggests they were taken at the RAF Display at Hendon in 1928, but that year it was held in June. So there's an error somewhere: either the day (it was on the last day of June) or the year (the 1927 and 1929 Hendons were both held in July). Or perhaps it wasn't at Hendon at all, but at one of the regional displays where RAF squadrons sometimes reprised their Hendon performances? It might not have been labelled until some years after the event. There's no real way to tell.
The photos themselves show reasonably well-dressed spectators standing in amongst their motor cars, watching two vics of what look like Armstrong Whitworth Siskins, judging from the sesquiplanes (click to zoom in). There's not enough detail to say much more, but that certainly fits the period: Siskins were highly maneuverable (the RCAF even used them for an early aerobatic team) and they featured at Hendon between 1925 and 1931.
C. D. Coulthard-Clark. The Third Brother: The Royal Australian Air Force 1921-39. North Sydney: Allen and Unwin, 1991. The classic history of the early RAAF (not that there is much serious competition). People, policies, institutions, infrastructure -- it's all here, even air displays!
Richard P. Hallion. Strike from the Sky: The History of Battlefield Air Attack, 1911-1945. Shrewsbury: Airlife, 1989. In a different way to Coulthard-Clark, another classic -- less detailed but equally comprehensive, including coverage of the role of combat air support in the various small and smallish conflicts in the interwar period.
Thomas Hippler. Governing from the Skies: A Global History of Aerial Bombing. London and Brooklyn: Verso, 2017. Follows up Hippler's previous work on Douhet by tracing a thread from air control to area or terror bombing to nuclear war the potentially unlimited (geographical, but also and more importantly legal) reach of drone strikes. Looks like an interesting update of Sven Lindqvist's A History of Bombing.
Stefanie Linden. They Called it Shell Shock: Combat Stress in the First World War. Solihull: Helion, 2016. Based on PhD research into hundreds of case files on British and German shell-shocked soldiers, which should be a fascinating comparison. Also examines the effect of the study and attempted treatment of these men on the practice of medical research itself. One chapter touches on the Angel of Mons, though alas there seem to be no phantom airships.
In an earlier series of posts I discussed Australia's first airship, the White Australia, which flew in 1914. It turns out that there was an earlier Australian airship, of a sort: the Airem Scarem. Indeed, according to a 1907 newspaper advertisement it was the 'First Airship below the line' (equator, presumably). From the above photo, taken in 1908, Airem Scarem was a trim little vessel, though the envelope is a bit on the small side and the propulsion system, which seems to consist of no engine and two tiny propellors fore and aft, hardly seems adequate. Fortunately the Airem Scarem was assisted in its flights by being suspended from a cable -- which has been crudely whited-out from the above photo -- because it wasn't a real airship at all but rather an amusement park ride, at Wonderland City in Tamarama, a beachside suburb of Sydney.