On the subject of well-meaning officials asking the authorities for clarification:
The Scouts used to use volunteer PPLs/club machines for flying days, on a cost-sharing basis. Then it ocurred to someone that the pilots' activities just might be construed as 'hire or reward' flights. The Scout movement asked the CAA. The CAA could only agree that such flying might well be regarded as such a thing. One senior CAA man told me that protection of CPLs flying people for money was a factor that could not be neglected.
End of PPLs flying Scouts.
Even before that, the chap organising the whole thing in the South-East told me that my Permit Cub 'might not be seen to be as safe as a C of A machine'. No Scouts ever got to fly in this genuine warplane - and I might add that my personal score of C of A engine/engine instrument failures leading to forced landings is two, v none in several hundred hours of Permit Cub aviation.