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Well Washington Works razors were made from 1848 to 1978 so that's a pretty broad span. That is definitely not made in 1978 but it's probably not as early as 1848. My guess is it's probably somewhere...

It's highly possible that it is not the exact same width it started out. A lot of water has gone under the bridge since it was new. And yes there was a variety of sizes made.

Edit: every time you...

https://shavelibrary.com/w/Wostenholm,_George_%26_Son

Try to get a close up of the engraving on the tang. If it says Sheffield England then it's after 1891. My guess by looking at the style of it is right around that time although if I'm not mistaken...