Roadster your pay scale isn't familiar to me I am afraid, we had differnt scales in the RAF and JT aircraft technicians were in payband 1, then they were sub divided by trade groups, riggers, sooties, leckies etc were TG 1, the scale was sliding with 1 being the highest and it went down as low as TG 16 (I think) TG 16 used to include, pen pushers, cooks, MT drivers, coppers and rock apes ect.
You were payed accordingly and no matter if you were a full NCO or not TG 1 JT's were payed more.
It was a simple reflection of the trade training you had recieved, your experience and your level of responsibility (unsupervised flight safety issues etc).
When compared to many other trades the consequences for making a mistake were considerably higher and your training and pay reflected this.
Remember that unless an apprentice (3 years intense trg) JT'S had to have passed basic training, initial trade trg (7-9 months) followed by five or six years (average) as a mechanic SAC, before being selected for fitters course if assessments were good enough.
Fitters courses for the different trades ranged from the minimum of 11 months upto 18 months approx, where you finished with an industry recognised engineering qualification.
Then and only then were you a JT.
Many of the NCO'S in other trades used to find themselves at the rank of CPL after just a few short years, when on a Cpl's course the techies generally used to be far more experienced and older than all of their course mates from other trades.