There's a whole genre of "a general history of lesbians/homosexuality in Britain" with approaches ranging from lighthearted (and often inaccurate) pop history to very serious academic studies and sourcebooks. (This genre may also exist for other countries -- I've collected a smaller set for the USA -- but I haven't run across them as often.) This one falls in the mid-range, probably intended as a textbook for a non-specialist social history course.