Unfortunately, ever since some Brize Norton station commander - who was a lousy pilot and an extremely arrogant and unpleasant so-and-so - decided that the well-proven VC10 ground school course was 'too long', much of the course was dumbed-down to Janet and John book level. So the delights of the whiffle tree were then lost to all susbequent students.....
As there were several whiffle trees, was that a whiffle thicket or a whiffle copse?