I suspect that a similar argument may have been used at Lee on Solent.
Not so Cluseau
At Lee the owners of the land the hangars or on is not the owner of the runway. Also the leases granted on the hangars are very short term.
WRT "unauthorised" departures the bit you're groping for is Rule 40 of the Rules of The Air Regulations
Movement of aircraft on aerodromes
40. An aircraft shall not taxi on the apron or the manoeuvring area of an aerodrome without the permission of either—
(a) the person in charge of the aerodrome; or
(b) the air traffic control unit or aerodrome flight information service unit notified as being on watch at the aerodrome.
Not NOTAMmed (yet) as closed today.