I agree with Say Again Slowly on
"...you need to have more knowledge than you are trying to put across. CPL teaches PPL, ATPL teaches CPL etc. etc."
as this is what happens in academic circles. Even without this example I also think that it is common sense to have a deeper understanding before you can explain certain concepts - sometimes having to explain in many different ways.
as for "...the requirements for CPL qualified instructors and a minimum of 300hrs TT on heli's, the number of new instructors has fallen through the floor"
I suspect that those finishing their CPL/IR (fixed wing) will take some time to realise that paying further to get the FI rating will not mean that they can earn a living whilst waiting for an airline job. If and when this happens, the f/w instructor pool may start to shrink.