Originally Posted by Sajen
... I think that it don't will be a letter opener since the handle look heavily used.
Maybe the previous owner(s) went through a lot of letters.
I wonder if it has been sharpened.
Then again, I use a razor sharp V42 dagger to open the occasional letter. The difference blurs.
p.s. - The USA and Canada used the letter mark 'STERLING', rather than a proof mark. So did the Irish! Bit closer to the UK again...