Some ideas;
Firstly I believe it was the practice often to take out the number when the order was taken, but there would be a bit of a delay caused by manufacture, fitting, proof etc, so actual completion and delivery might easily be a number of months later
Secondly, I don't know Boswell's history in detail, but the move may have involved being at two addresses during a transition period. Strand is a 'shop' type address/area. Possibly a workshop remained in Edmonton?
If the barrels were replacements, I would expect a later number to have been taken out for them I think.
Trigger guard sound like a replacement 'borrowed' from a later gun.
