There is a chance this is a Yeomanry sidearm from mid to late 1800s
after doing some more research I found some images on google that suggests a crown being part of yeomanry symbolism and the Y, of course, meaning "Yeomanry" (maybe). If you type Yeomanry in to google images you get a lot of Crowns and and the letter Y.
It is possible that this sword is from Australia or New Zealand (Canterbury Yeomanry Cavalry??).
I would do some more but it's late and I'm getting tired.
I hope someone else takes an interest because I don't see myself solving this one alone.
Thanks for all the replies so far!