Another great find from John Gm.
This is a decorative plate from a pistol or musket and dates from around the 17th Century. Notice the ominous faces above and below the oval recess.
Update from the Curator of Firearms - Leeds Royal Armouries...
"The proportions and general form are correct for an escutcheon plate from a large pistol or longarm of c 1680 - 1750. I would place it on a relatively inexpensive civilian piece, though it is difficult to be sure. I'm not sure we have one quite like it, but I'm pretty happy with the ID as a firearm component. The relatively basic decoration and find spot could point to a trade gun".