Was the airfield Joyce Green?If so, is this beasty the barrier on Dartford Creek? Although it is actually on the River Darenth, Google labelling ……
Well the only RAF base that took its name from a road would appear to be RAF Guston Road, but I've been virtually up and down Guston Road and can't see and concrete monstrosities.
Is it one of the sound walls used for aircraft detection?
Not that clever .Are you sure its not in Berlin or Russia .