the meaning of "acting as a pilot" will probably only ever be determined in a court of law following an incident or accident.
Exactly. The fact that this has never to my knowledge come to court in the UK means that we seem to have 'got it right' without interference from the CAA. I'm guessing most PPLs when taking friends for a ride in an a/c with dual controls let them 'have a go' without accident or incident.
I do seem to recall the total loss of an Airbus A310 in Russia years ago when the captain let his son 'have a go' but a Cessna 150 is rather different, I'd say!
TOO