Just re-read the version(s) in the DT, and as posted by Dan above. They both mention Dungeness rather than Dover. To my mind this doesn't make sense, Dungeness and Romney Marsh are about 10 feet above sea level and would not be visible until you were about to run ashore. (Its different now of course with the lighthouse and the Nuclear power station - can't miss it!) You need to stand well out into the Channel after sighting Fairlight to avoid Dungeness, and the cliffs of Dover are the next obvious mark that you are clear of the hazard and can bear away for South Foreland to take you into the Downs.