Sorry to add another possibility but the date letter is 'h' for 1882-3. Maker is Edwin Page 1st registered with Birmingham Assay Office in 1879 first as a jeweller then as a chain maker, first address given as 25 Hylton Street and then 33 Hylton Street, Birmingham. The lack of a duty mark was because these kind of lockets were exempt from hallmarking and therefore exempt from duty. Although they are nearly always hallmarked usually in either Birmingham or Chester. I hope this helps.