It sounds like a bronze 1897 diamond jubilee medal. Not worth a great amount of money, but I suspect, as is often the case, the proprietor of the collectable shop also has no idea what it is! If it's a nice one, get it for a tenner. More if it's perfect. Although I normally come across the silver version. Geoff, is this the bronze diamond jubilee medal, and are they as common as the silver version?