I help out in the tower sometimes at Sandown,I am also a commercial pilot.I can personally say that the A/C in question is not based on the Island.The resident pilots on the Island would be banned from the club and that sort of behaviour is not tolerated!
The Island is quite rural, however our connection with aviation is very strong and very professional.
(Islanders,Trilanders,ARV,GKN,Saunders Roe,Bae Systems Etc)
It could have visited either airport on the day,it was not one of us.