British Sterling card case 1851 Nathaniel Mills

This tiny little box has script engraved initials W.A.R. on the top.  The swirl design also covers the bottom of the piece.  I've recreated the marks as they are so tiny it is impossible to photograph them well. I'm not sure of the weight, although it seems heavier than a sterling item of this size should be.  Any information or idea of it's original use or estimated value would be greatly appreciated!

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