If I have interpreted the clues correctly:- Box Hill appears to be described as one of Britain’s most iconic climbs with an average gradient of 5%, (1:20) throughout its 2.5 km length. It is also referred to as ‘zig zag’ hill for the couple of hairpins featured which apparently gives climbers an "Alpine" feel.
Dunsfold Aerodrome lies approx 15 miles southwest of Box Hill and became the test centre for Hawker Siddeley. On 4th September 1953 it was announced by the Royal Aero Club in the Press, that Squadron Leader Neville Duke chief test-pilot of Hawker Aircraft, exceeded the world speed record during trial runs over the official 3km course near Littlehampton the previous Monday evening. He attained 741 m.p.h. on each of two runs in one direction and averaged 703.5 m.p.h. in the other direction, the average speed being 722 m.p.h.