Membury is marked as an airfield on the charts, not as a disused airfield. It's a very quiet airfield, I don't think I have ever seen anything take off or land there. The whole point of an ATZ is that you need permission to enter it & since Membury doesn't have enough traffic to justify having someone sit by a radio all day it will effectively be a Prohibited area for most of the time.
Do we really want small, unmanned airfields getting ATZs? Where will it end? Brimpton, Clench Common, Manton, Firs Farm, Rivar Hill, Hampstead Norris? They are just the ones marked on the charts, there are plenty more unmarked airfields in that area. Talk about complicated airspace . . .
cjm_2010, sympathies for an unpleasant experience. I would also report it as an airprox, they may be able to trace the aircraft through radar recordings. The pilot must have come pretty close to the mast.