Hi and welcome to the forum Fad0025. How about a little bit of help here? What is the diameter of the coin? Young Head Victoria coins were issued in several denominations in the 1840s, but I haven't found anything in a preliminary run through of the 19th Century Standard Catalog of World Coins with a reverse that seems to match what little is visible in your picture. If it is silver, in that condition it's probably only worth the bullion value, but tying down the denomination would greatly help in determining value.
I suppose it could be a Half Crown, Roy. But as you point out, there's not a lot of info provided by the OP.
That was my first thought based on the overall appearance. I didn't realize at first that the reverse is upside down in his photo, so mayby 'BRITANNIARUM" has worn down to "BRITTANIA".
It is either a young head Crown or half crown and is worth no more than bullion for .925 sterling silver (The crown is about the size of a silver dollar and the half crown about the size of a silver half dollar). Of interest, one of old slang terms for these coins early in the 20th century was dollar and half dollar - not just in size but in value, as at the time £1 sterling was worth $4 US. Hope this is of some use. Regards, PAB