Peter (Peter has passed away as advised by wife Lynne probate email sent SF case 01976178) Anderson 
A Structural Atlas of the English Dialects [PDF ebook] 

First published in 1987, this atlas identifies structural patterns which exist in the sound systems of the dialects of England. It regards variation, not as something to be ignored or avoided, but as a central and essential feature of dialect, which must be accounted for in a systematic way. The study identifies some of the more prominent structural boundaries between dialect areas and argues that discrete boundaries do not exist: rather there are a number of areas separated by bands of dialects in which conflicting partial systems exist.