Back in the day the USAF crews would book their F-111s into the Tac Route and be told 'you will overtake a Jet Provost between EP X and EP Y. They were convinced that the RAF had some pretty heavyweight computing power in the 1970s.
Apparently their faces were a picture on visits to the cell when they saw the perspex boards with time/EP graphs and the chinagraph lines crossing at the overtake point.