As you know the name of the sitter, presumably you know her year of birth? At a guess, she looks to be in her early twenties in this photo, so you should be able to come up with an approximate year that the photo was taken.
Added: if Nellie was her given name rather than a nickname, there is a birth registered in Shardlow in 1900 which may fit. That also tallies with Carol's estimate of 1920s for the photo.
Added: For confirmation, the 1901 census has this Nellie with parents William and Elizabeth plus siblings, living in Long Eaton.