"SOU needs to encourage GA more"
Not unless GA pays a meaningful rate...which the lighter end of GA probably won't want to pay. Aviation revenue derived from GA will never plug the hole created by the lost non-aviation revenue associated with passenger operations.....car parking, shops, cafes, advertising etc etc. An increase in top end GA possibly might help, but even then, without havng a revenue breakdown , it probably wouldn't help that much, and SOU would be trying to draw traffic from established top end GA airfields...e.g. Biggin and Farnborough. Reality is hitting home.
HB