Nope, wouldn't be the original sight.
Watsons began in Creemore Ont in 1896 then moved to Niagara Falls in 1910. When they got their patents they moved to Toronto in 1923.
About the only guy I know that you would have any chance of finding an insert for your sight would be a guy on Ebay named Pallet25 who is at alot of the Ontario gun shows. His name is Paul and I used to have his email addy but can't seem to find it now. His wife Leeanne (I think) does most of the computer stuff, real nice lady. He seems to have an over abundance of Watson sights and parts. I've bought a few Watson 1" apertures off him over the last couple years and I see he has some of the front sights listed evey now and then but Watson is a pretty rare sight, especially a tang sight to come across, they didn't make alot of them back in the day. Good luck.