I think Sandy may have hit the nail on the head "in reverse" - so to speak .
Middle-distance and long-distance runners need to do a certain amount of interval running up steep hills as part of their overall training programmes .
You haven't mentioned the top towns Jayne but I wonder if the industrial West Midlands (where I live ) figured ? It's not a particularly "nice" area but there is a surprising amount of high ground and steep hills in the metropolis itself - Turner's Hill , Barr Beacon , Warley Woods , plus lengthy canal paths to keep out of the traffic .
Having said that , wasn't Steve Ovett Brighton - based when he was winning all his medals ?