If you are taking members of the public who have no intention of completing a PPL course on a flight over their house or a prominent tourist location (which is not in the local training area), no amount of briefings or letting them have a go at the controls will make it anything other than illegal public transport.
So, to take a hypothetical but perfectly possible situation for me....
Someone is bought a trial lesson voucher as a birthday present. He comes to Tatenhill, and asks if we can overfly his house, have a look at Alton Towers, and can he have a quick go on the controls too. We do all that, and I demonstrate a bit of hovering and an auto-rotation...just to show him what helicopters can do. He comes back, and announces it was the most fun he's ever had in his life, and he wants to do the whole course, starting next week. He'd been thinking of it, but didn't want to feel like he was committing himself by saying anything at all before the flight.
DFC, are you saying this flight was illegal? After all, I couldn't have read his mind.
(Hypothetical situation, but not too dissimilar to what has happened several times)