I have three 1860s guides (Blacket's 1862, Hall's 1863 and Adnams' 1864) - these are not directories, they do not list local businesses, which only appear if they paid for advertising space. The only photographer to do so was E T Brooks in Hall's 1863 Newbury, Speenhamland and Hungerford Guide.
The starting point for the research of Newbury photographers is "A Directory of Photographers Newbury and District 1854 - 1945" by P. Cannon, in conjunction with Newbury District Museum. ISBN 0 9501945 73