Manston runway vs Gatwick 1 runway :
Here are same-scale Google Earth images of Manston (top) and Gatwick 1 (bottom) runways.
For Gatwick the usable length of its main runway (08R/26L) is 11,178 ft (3,407 m) when aircraft take off in a westerly
direction, and 10,863 ft (3,311 m) when takeoffs occur in an easterly direction.
Manston is double ended 9,016ft (2,748 m), and there is no difference.