When an aircraft fired on another and missed the bullets would eventually strike the ground still travelling at some speed. During the BoB there must have been a lot of lead coming out of the sky, not to mention splinters from exploding cannon shells, bits of aircraft etc. I know that members of the Women's Land Army asked for and were issued with Brodies because of this and soldiers had to be drafted in for the hop picking because many civilians decided to stay away, I have, however, found no mention of actual casualties. Were there any?
Yes, without doubt. How much is immeasurable. Indeed, some of the incidents blamed on the Germans as deliberate may even have been accidental RAF strikes. An example is the March 1941 raid on Newark: a recent author thinks that the Luftwaffe machine-gunning may actually have been AA Lewis gun rounds coming back down to earth that killed factory workers (but this is highly debatable/contentious, imho)
Wouldn't dismiss it out of hand though. I visited Baghdad just after the end of the Iraq Iran war and heard from a number of people that when the Iranians raided the city most civilian casualties were caused by Iraqi small arms fire coming back down and hitting people sleeping on the flat roofs.
