The correlation between regions and counties is not exact. When travelling across England one county or region gradually merges into the next until you suddenly realise you are in a completely different environment.
English Heritage has produced an excellent set of booklets on “historic landscape characterisation”. You can go to the download page by clicking on the link below.
On the following pages, as well as the barns I have visited in each county, I have included links to more general resources which I hope will be of interest.