Think these are Exeter and presume they're the marks for Richard Ferris. Date letter is unreadable unfortunately - could be the f of 1791. Why the letter series went r f t I am not sure. The rather naive bright cut is remarkably similar to that on a pair of tongs I have, possibly the same engraver. I assume the other rubbed mark is the three castles of Exeter. They're a little battered and bruised.
Many thanks Frank
Sorry the hallmark pics came in upside down