Fascinating article. It seems ready made for a geographical analysis at a finer scale eg settlement size as a variable, suburbs vs inner city.
Also, for several of the maps, the Mackinder line (mouth Tees-mouth Exe) seems discernable. It's a geological/climatological divide, and while it seems unlikely that living on chalk or granite affects one's tendency to neuroticism, it very likely does influence cultural patterns that do affect personality.
Has anything been done to compare these results with the mapping of genetic population groups recently identified from DNA?