Always good to hear praise for a system of which one was once a part.
FWIW, my memories of the appo system at Cosford started in 1976 when I trained alongside them as a direct entry (DE) Nav Insty. I wanted to join as an apprentice myself, but was unable to locate my ex-Headmaster for his signature on the forms, as he'd quite inconveniently taken his family overseas on holiday. Thus I missed the window for that year's entry and was "persuaded" that DE was the route for me.
Anyhow, back in 1976 the system was for a 3-year apprenticeship (as opposed to 15 months training for a DE), passing out as a J/T. Appos were either pure Nav Insty (L Tech NI) or splitbrain Comms/Radar (L Tech AC/AR). After passing out as a J/T, an appo could expect to get his tapes up after a year, providing he got the assessments required (two sixes as I recollect). Time promotion to Chf Tech disappeared in 1975 I think, but to Sgt (4 yrs) it was retained until about 1979/80. Those of us who had joined up in the expectation of time promotion, but who failed to be selected under the new system had reserved rights of pay to the next rank up, providing you had the promotion exams under your belt.
Forward to 1984, and I was back at Cosford as an instructor. The appo schemes were just the same except we'd all been rebadged. L Fitt NI (the DEs) were now L Tech FS (Flight Systems), L Tech NI (the appos) were L Eng Tech FS. For comms and radar it was similar (L Fitt AC --> L Tech AC, L Fitt AR --> L Tech AR, L Tech AC/AR ==> L Eng Tech AC/AR). I don't know when the scheme changed, but when I left Cosford again in 1987 it was still as above.
Back then, it was a bloody good training system overall. I can't speak for the appos, but us DEs didn't do a lot of hanging around - it was 15 months of technical training. I may no longer employ any of the technical knowledge I learned at Cosford to earn a crust, but it was all good background for what I do now. The overall ethos of integrity and attention to detail which underpinned the RAF techie training system has stayed with me, and has (directly or indirectly) opened many doors for me over the years.
I'd like to think that Ofsted saw some of that when coming to their conclusions about modern RAF apprenticeships.