I understand that part about the school but surely this is purely an internal thing- I just don't understand from a regulatory perspective what stops a person from being P1?
Is it the insurance (if so does the CAA view the flight as being not legal?), not being able to put their name on the tech log etc..?
Both aircraft are the same after all.!
It would be no different to someone who owns their own plane say a C152 letting a friend fly who also holds the same license? He would still be able to log P1... as far as I know..