The Sussex accent is virtually dead. It has been replaced by a fairly nondescript "Estuary" accent that can be heard anywhere within a 60-mile radius of London.
Occasionally I hear a rural burr from some of the older people in town, but it's nothing like this wonderful recording from 1959. Click on the John Nash picture below to visit a page featuring Harry Burgess of Firle:
The British Library's National Sound archive is a wonderful resource, with recordings that include Tennyson, Florence Nightingale and Arthur Conan Doyle. But my favourite part of the archive is a collection of recordings of accents and dialects, arranged by county.
Another favourite of mine is this one from the Isle of Wight. Mrs Sheath has a wonderfully rich voice and if you listen carefully, you can hear a clock gently ticking in the background. As for this accent, it might as well be in another language.
Television, cars and people like me have all helped to erode local identities and sadly, we will never hear a voice like Harry Burgess's again. Thank God someone had the foresight to record these accents just before they disappeared.