Hi:
I recently aquired a beautiful piece of Sheffield silver. It may be a tray, although it isn't shaped like trays I have seen. It is marked with what appears to be a lion on one side, and a horse on the other side, a crown at the top, and perhaps a shield in the center, below that is says James Dixon & Sons, underneath the name it says Sheffield; all this is on a small plaque attached to the wood. It also has J D & S stamps each in a separate small square on one of the hinges. There is a single letter S stamped on another hinge.
It is a large round tray type item. It has greek key etching all the way around. Small beading/ balls all the way around. The center is raised, and has a mirror. The back is made of wood, with hinges that hold the morror in place. It has 4 ball type feet.
I have no idea what this item's true purpose is.
It does not have any marks regarding whether it is electroplated, sterling etc...
It also has the number 400 stamped into one of the hinges.
Any information on age, whether it is likely sterling or electroplate, purpose, value, history etc... would be greatly appreciated.

Or if anyone knows of any free resources I can use to research this item, I would really appreciate it.
Thanks so much and HAPPY NEW YEAR!