Radar ATCOS Paid Less Than Tower ATCOS
It has always been my experience that the BASIC discipline in ATC is Tower & the ADVANCED discipline is Approach & Approach Radar (at an Airfield).
The pay scales, wherever I have worked (including NATS), have ALWAYS reflected this.
I was at Jersey for the last 30 years & in the last couple of years we had a Tower only rated ATCO (failed Radar rating validation) who was on approximately half the rate of the lowliest Radar rated ATCO.
The standard progression was to obtain & validate your Tower rating first, & then move on to do the same with the APP & APP Radar ratings. Once you had done this (obtained & validated the APP & APP RDR)you then worked approximately 2 years before achieving PPR (access to the higher salary bracket).
We NEVER had Tower ONLY rated ATCOS who were on a remuneration that was anywhere near to Radar rated ATCOS. Those Radar rated ATCOS were, incidentally, all Tower rated & validated.
I hope that this is relevant to your situation.