Well that's just curiouser and curiouser! Thank you Pete, for that letter, and thank you Taphappy for your thoughts as well.
The wording of the letter certainly suggests that there was some sort of education to be expected while on deferred service - though without the FIFTH paragraph, as you say the later letters were, 'academic knowledge' could well be anything. Perhaps the intended meaning was to suggest that studying something, anything (at university perhaps) before call-up would help to put recruits into the 'study' frame of mind and so adjusting to the intensive learning of "specialized Service knowledge" once on a course would be that much easier.
I'll continue to ponder it while awaiting the arrival of Danny for his next no doubt thrilling installment
Cheers, all, and thanks again,
Adam