KK Location
I've kept all my maps from my Herc' nav' days and in the old one- inch OS sheet 182, Brighton & Worthing, it shows quite clearly that Gatwick was in Surrey. The county boundary was on the old Horley to Crawley road at a place called County Oak.
My guess is that under Local Government re-organisation in 1974, when, if you remember, places like the counties of Avon and Cleveland were formed, Crawley in West Sussex had it's boundary changed to absorb the airport - perhaps because the vast majority of the KK workforce lived there.