It would seem to be too small for this but possibly so.
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Having looked at further illustrations of bayonet scabbards of the period I now believe that is what it is. Thanks to those who have helped
I am adding a scale to assist
looks like the end of a scabbard, like for an infantry sabre, a scale would help for all photos to give a better idea.
Not an expert but looks like part of a (bayonet?) sheath or scabbard. Example below:
British, Baker Rifle sword bayonet & scabbard Baker Flintlock Rifle Sword Bayonet (historicaltwiststore.com)