Back in the late 60's when I did the FS course, the public service had divisions and ATC were Division 3 and FS were in Division 4. I recall that was based on amoungst other things one's level of education. The course prior to mine were all Communication officers (Comm Officers). I knew many FSOs that went into ATC over the years.
I later left FS to take up a flying career. I thank my FS years for teaching me how to type and say 'No' to ATC!
