Hi, The maker mark looks like Stephenson & Sons. You’re correct with the ‘n’ for 1905/6,
The 1732 could be the scratch weight, i.e. the weight when it was assayed or perhaps a pwanbroker has put his number on it, presuming it had been pawned at some time in the past. If you weigh the salver you could compare the weight with 1732 and see if it makes any sense.
Hope this helps,