At 17mm it will be either a Victorian Silver 3 or 4 pence, the denomination and date should be on the other side.
http://en.numista.com/catalogue/pieces5839.html
http://en.numista.com/catalogue/pieces13827.html
http://en.numista.com/catalogue/pieces5839.html
http://en.numista.com/catalogue/pieces13827.html





















