I have found Google Books can turn up some interesting surprises. When searching, especially for older volumes, remember that the scanning software used will usually have read the old style letter s as an f. So, for example, a search for Merftham is necessary to find very old references rather than Merstham. Also a good idea to mug up on older variations of placename spelling such as Reygate or Ryegate instead of the modern Reigate.