This Smith worked in both sterling and plate. On plate, numbers generally identify what the piece is. Sometime a two digit number can be a year mark. In this case we would expect 1950 as the only possible date given the years of the company's span. But it is more likely an internal code related to a worker or the piece. If not plate, notice the 1 is out of register with the 900. .900 is the mark for coin silver. But again, not likely since Smith is known to work in sterling rather than coin.