That number should be around 1874. A view of the proof marks might add a bit more to the story. I gather that he was established around 1850 and was formerly at Duke Street, Manchester Square, Paddington, St. Marylebone and 172 Strand, London. I can't seem to get to the date he moved to 32 & 33, Lower Loveday Street, Birmingham. He may have used both addresses for a period. Looks like the book with records to your gun may be missing. Lagopus.....