That's it for the phantom airship scare of 1909. It's been interesting for me, as I haven't looked closely at this material since I did my 4th year thesis some time ago (the 1913 scare made it into the PhD, but not 1909). It didn't last very long, only a couple of weeks. At first, the stories were presented as a curiosity, localised to East Anglia. It seems to have been the Conservative press which took most interest at this stage, though it seems to have been divided as to whether a British aeronaut was responsible or an airship flying off a German warship. It was only when two separate sightings of the airship took place in South Wales — by dock workers at Cardiff and the Punch and Judy showman on Caerphilly Mountain — that Liberal papers such as the Manchester Guardian started reporting it. It seemed that something was going on.
But almost as soon as the phantom airships became 'serious' news, scepticism set in. Percival Spencer announced that his family's firm had recently sold several small airships for the purpose of advertising. Even though he gave no actual evidence of any connection between these and the scareships, it seems to have been good enough for all the newspapers examined here (bar the Norfolk News): there are far fewer stories about the 'fly-by-nights' thereafter, and those that do appear are sceptical or humorous. And, to be fair, real evidence of a hoax did turn up, in the form of a crashed airship and a claim that Jarrott and Letts, purveyors of fine motorcars from the Continent, had been towing it around the Eastern Counties at night as some sort of advertising stunt (which I still don't understand, but never mind).
That doesn't explain the Cardiff sightings, of course, nor the Irish ones nor the North Sea ones nor the (possible) Belgian ones. I don't believe that there were actual airships involved in these cases, except perhaps the last two. No archival evidence has ever emerged of anyone flying airships over Britain at this time, whether homegrown or foreign, other than those which were well-known at the time — Willows, Spencer, the Army. Maybe meteors, maybe fire balloons, maybe luminous owls. It doesn't much matter to me. What's more important is why various explanations were offered and why they were accepted (or rejected).