I used to work at Sherburn...instructing...so I know the people in question quite well; I've flown with them all at various times.
It always surprised me that Jan Coster claimed that the instructors were fairly paid and that she could manage OK on the income. Makes you think!
I suppose that some evil-doer might have slipped the drugs into the aircraft whilst the crew wasn't looking....I mean, that's possible....isn't it?