I have a wonderful book of advertisements in ‘The Times’ from the 1870s. As well as being a mine of information about everyday life in London at that date, there is also a section of personal advertisements, many of which could be the basis for a novel.
Looking for a plot? How about:
C.C.C.C. Do not despair, my Marguerite. Only have patience. I hope we shall meet on the 3rd at P. Be cautious and attend to all the advice I gave you. Do write to the London address if you possibly can, and tell me what has happened that prevents your writing. If I wrote in l.j. it would betray us. Thine for ever, B.B.B.B.