This led me to an internet research rabbit hole, via http://www.ukserials.com/ to the crash report (years ago) of http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/8587389...

It drove home that the aircraft doing low-level flights have very little manuverability option when flying at 400kts (~200 meters per second). Dodging a drone would be infeasible even if you could see where it was. Transponders with LOS limitation might be of limited use given that the terrain is extremely hilly and the aircraft could come round a corner in the valleys or over a ridge.

It's also a major tourist area, just the sort of place that people might want to send up a photography drone...