JP
The RAF was way behind the times between the wars; everything being run by the '2-winged Master Race'. I don't say that as a form of envy, having been a nav, but as a statement of how it was.
Commissioned pilots would do one flying tour and then have to choose a 'specialisation' such as engineering,navigation, instructing etc. In fact the only other branches were Medical,Padre type ones.
I've just finished a great book by Dickie Richardson, entitled 'Man is not Lost'. He joined as a pilot in 1933 and then four years later went onto a nav' course. He wrote the AP1234 Navigation Manual, bit like a Part 2, in 1941.
Because navigation had been poorly understood and taught it meant at the start of WW2 virtually no senior officers knew anything about it, this meant the necessary aids to help Bomber and Coastal Commands find their targets and their airfields on their return, were not in service until 1943.
So JP you can see why ATC was late being developed.
I gather that it is almost back to the bad old days now as everyone relies on GPS - can that fail, I don't know? What happens if it does?
BW