by early 1959 the Air
Traffic Control School concentrated its efforts on training aerodrome and approach controllers through the JATCC and radar director and
talkdown controllers through RAC courses using CPN4/MPN11 radars. These were the infamous Red and Black trucks positioned at RAF Sleap
airfield to the northwest of Shawbury. The CPN4/MPN11 radars were interesting pieces of equipment; with two cramped combined search
and precision approach radar positions in each truck and a particularly challenging curved PAR centreline. The two radar trucks operated
simultaneously, with aircraft being positioned for approaches to two different runways at Sleap.
Long before the emergence of the current overprescriptive Heath and Safety at Work legislation, prospective controllers had to be ready to ‘tweak’ the radar controls with a small screwdriver, or plunge their hand into the rotating radar equipment behind them to physically turn on the
rain plates; many controllers hands from this era still bear the scars from these days.
(extract from The History of the Central Air Traffic Control School)