Quite correct K&C, but just to "dot the I's". The original avionics guys went through Locking and I think the first super techs, radar and comms, went through Cosford starting with the 104th passing out in early 1966. I also seem to remember that the super tech training was aimed mainly at first line rectification whereas single trade craft courses included 2nd and 3rd line techniques, certainly for the avionics guys.
I was a 3 year, pre-super tech Locking App. and it was fairly normal to pass out at 18 as a J/T, CPL at 21, SGT at 25 and C/T at 30, subject to passing the exams, boards and having the right numbers.