At a guess I would say they are at either Stafford or possibly Ruddington; maybe even Syerston.
I've never seen the present winches used by Air Cadets; I believe they can have up to 6 cables.
I remember the days at Halton during a course when we would have 2 x twin drums parked side by side and the driver would jump in and out operating all 4 cables one after the other. We could sometimes use 2 x single drum V8 powered winches side by side too but usually that was normally on a separate 'line' some distance away; we were able to use the whole of the grass airfield in those days rather than just the narrower strips used nowadays.