Trial Flights
I don't think the CAA have been "trying for years" to clamp down on 'Trial Flights' at all.
Flying an aeroplane is not an experience that anyone may have without undertaking an actual lesson with a 'Flying Instructor'. It is quite proper and not a masquerade to have a 'Trial' first before commiting themselves and their money to a course.
To have a 'Pleasure or Sightseeing Flight' with a AOC operation would not allow 'hands on' or any Instruction to be given during the flight. Indeed unless the Pilot was also an Instructor it would be unsafe. An Instructor is trained and qualified to hand over control and take back control and deal with the sometime unfortunate handling characteristics of the nervous and occasionally terrified student.
Even if the punter has no intention to continue with training, it is in the hands of a trained and qualified Flying Instructor that they are able to sample a full experience of flight.
A BLOODY GOOD ADVERT FOR THE PROFESSION AND THE FLYING INDUSTRY, AS A WHOLE, WHEN DONE WELL, AS MOSTLY IT IS!