Dublinpilot has made some good points there.
If four aircraft infringed your zone when the norm is one or two, wouldn't that make you think that maybe some duff information was given out?
We know that there are some idjits out there and we all have a responsibility to keep an eye for them (just as the idjits have a responsibility to stop being idjits) but most pilots are conscientious and therefore I might start to think that there could be another issue.
Cheers
Whirls
PS - any of you Weston glider guys flying over Newbury Show on Saturday? Just wondering as I was there watching the Silver Wings parachute display team!