From the Met Office - MIDAS Land Surface Observation Stations Data
http://badc.nerc.ac.uk/data/ukmo-midas/ UK data from 1853 to the present day.
See the web page for the data availiable - You need to apply for access as they don't want it republished, so hopefully you want it for academic research purposes rather than commercial.
EDIT - re-reading your original post, the above is probably inappropriate, but I'll leave it up as a useful link
