I would agree with mr aft cyclic that this is an issue.
now there are lots of clever people around who know the law a lot better than me
but there seems to be several people around who have a very loose idea of what constitutes a "private flight" which to me sounds like a charter.
it may start with an owner asking a "mate" (who may be an PPL instructor operating under grandfather rights or who may just be a regular PPL with a few hours) to come along with him in his own aircraft to some event and to fly the owner back in the evening as he will be "p***ed by this point.
before you know it the owner is asking him to do little jobs for him, pick this person up here or that person up there and fly them to wherever and of course they will pay them either in free flying the promise of further free flying or just in cash.
and this can develop into them basically being a ppl charter pilot, the passengers may not be actually handing over cash but there is no difference from a charter.
all of this undermines the point of getting the CPL and leads to a situation which we have got now where there are very few proper jobs on single engine aircraft (instructors excepted) because there is no money in it.
on top of this we have got extreme examples, I heard a story of someone who was allegedly caught at battersea walking out his passengers to the aircraft to do the charter dressed in the white shirt/4 bars, who turned out to be PPL who didnt even have a valid LPC on the aircraft he was about to fly.
I think there is lot more "grey charter" around than most of us realise.
regards
CF