Under English law, the land owner also owns the airspace above the land unless specifically excluded in the lease or transfer. The construction oriented folk on here will be familiar with that notion and will no doubt have had at some time to have negotiated oversailing rights for the operation of tower cranes etc.
There is legislation to allow overflight by aircraft without causing trespass but how close does the regular practice of throwing pal,s over the land come to causing trespass and pi**ing off the neighbours?
As I said, the aero modeller is doing nothing illegal. Get him on board, befriend and educate him.