During my sporadic research I've come across a few useful theses whilst browsing the web...
The Management of Road Traffic in a Rural County
This thesis concentrates on the interwar period in Herefordshire. While it obviously concentrates on road and transport issues, it also provides some interesting background information (including a useful population density map, and a map of the principle roads throughout the county).
The British Union of Fascists in the Midlands, 1932 – 1940
An interesting study of the BUF in the Midlands. It doesn't mention Herefordshire, but is still useful background reading as the Midlands isn't a million miles away.
Able Bodies: Work camps and the training of the unemployed in Britain before 1939
A study of Britain's instructional camps, where the long-term unemployed were given manual labour in order to 'harden them up'. There was an instructional camp near Shobdon in Herefordshire.
An Uneasy Alliance? Welsh Nationalism and Roman Catholicism
Interesting reading given that, in the VBCW universe, Welsh nationalists are operating along Herefordshire's western flank.