I've copied this over from another website,
http://www.angelfire.com/tn/goldengreen/manoke nt.html
- looks like quite a touchy subject
The division may have arisen when the Jutes, who settled in Thanet over 1,500 years ago, moved into the area we know as Kent, calling on part East Centingas and the other West Centingas. There have been two Kent dioceses since AD605 - Canterbury (East Kent) and Rochester (West Kent). Unfortunately, it appears that the Men of Kent resisted William the Conqueror more stoutly than the Kentish Men, who weakly surrendered. Afterwards, according to Alan Major in A New Discovery of Kent Dialect, the bravery of the Men of Kent made them proud while Kentish Men were believed to be weak-minded, and so a keen rivalry developed.