I'm not sure how helpful I can be, since I'm in a different country with different systems...but recently I had to find some historical material, which involved a very arduous search - I ended up contacting about 15 different people/organisations before I found what I needed. However, it was a national archive instituion which eventually helped me - is there a British archive service? There must be - and they should have an online database which you can search. Find a helpful archivist and you'll be set! I also searched a whole lot of online database searches of other archival institutions specialising in my area of history.
Good luck!