Found on a knee buckle with the London Lion Passant Guardant of 1756 — 1784. Stylistically it could be anywhere from 1760 —1780, but to me looks stylistically around 1765.
This mark, which I thought was an FR but which could well be IR or JR is not in Grimwade although John Rich 1765 mark (Grimwade 1635 ) as smallworker is close. Grimwade 1635 however appears not to show the bar on the first letter. Rich was given in the PR1773 as a bucklemaker and had bucklemaker marks entered in 1780.
The entry in "Wine Labels" page 177 casts doubt on the attribution of some marks to Rich, commenting of his supposed 1780 mark that "some of these (wine ) labels can be realistically dated to at least ten years earlier than 1780." This mark may therefore be another unregistered mark of Rich
If the mark is FR then I have no suspects for it .
For completeness, below is what I believe to be one of John Rich’s 1789 bucklemaker marks. It is on a shoe buckle with the London Lion Passant Guardant of 1756 — 1784, but which stylistically is certainly c1780 -1785
I believe this mark is probably Grimwade 3678, which he found on a winelabel of around 1794 and attributed tentatively to John Robins, but I feel is likely John Rich - a well known maker of winelabels