Casting my mind a long way back to when I was at school and leafing through glossy brochures from the various Branches, I seem to recall FC had a hierarchy that went something like Weapons Ctrl - Identification (IDO -Surveillance now) - SAM Ctrl if you couldn't do either of the others.
Back in the 1970s everyone in the FC branch started off as a Fighter Controller (FC) then went on to become a Cheif Controller (CC) and then a Control Executive (CONEX). Along the way you could also pick up identification qualifiacations such as Display Controller and NATO Evaluation officer (EO).
if during initial training you couldn't pass the course you were chopped; if it considered this was for lack of capacity though you were still safe (i.e. You could safely keep aircraft apart - but could not simultaneously bring the required ones together at the same time), you were offered ATC and sent off to Shawbury.
The problem with this system was that the failure rate averaged around 80%. As a result the branch was redesigned with 2 streams - Control and Reporting.
After initial evaluation recruits were either streamed as Controllers or Identification and Reporting Officers - IDROs (If you want to be an IDRO clap your hands! - swing hands wildly towards each other and miss). Controllers went Intercept Controller (IC) then Fighter Allocator (FA - new name for CC); Reporters went IDRO then Track Production Officer (TPO - new name for DC); then branch recombining at Master Controller (MC - new name for CONEX). The Reporting stream picked up EO and then new qualification of Data Link Manager (DLM).
The new qualifications had to be given by someone, so in the early days some of the old hands acquired the new qualifications along with the old.
ORAC - FC, CC, DC, EO, IC, FA, IDRO, TPO, DLM, MC (plus various CQ and LEO tickets).
I did do a one year "bad boy" tour as an Ops Officer at LU including 4 months as Ops 1 and South Atlantic SFSO at Stanley as well - but that's another story......