When the CAA's predecessor ( Board of Trade? ) decided to start its own Air Traffic Control cadet courses in the early 60s, the first part of the 3 year course included a PPL. The first 33 courses all the way through to the mid 70s had this 'privilege' and quite a few ATCOs went on to obtain CPLs and become airline pilots.
From the mid 70s the 'bean counters' took control and cadets were no longer trained on all three disciplines, ( Aerodrome, Approach and Area ). I know of several ATCOs at LHR with 20 plus years experience who have never done radar.
When No2 son became a cadet in '96 the flying was limited to 15 hours. Even that was cut out eventually.
When No1 son did his RAF Flying Scholarship in '86 I think it was for 35 hours and I paid for the extra 3 required to obtain the licence, which I don't think he has ever used!