I can’t photograph the hallmark because the stretcher of the bun warmer is in the way. I will describe it and hope someone will know what it is. FBRSSEP then a diamond with a circle on top with an I in it. In the diamond top point a 15, middle an R with a lower case a, right point a P, left point a S, bottom an O. I tried to add a picture but I guess I have too many pixels
Hi, what you have is not a hallmark but a design registration number. The Ra in the centre is Rd, the 15 is the day number, the P is the year (1877) and the O is the month but O was not used could it be a D in which case it would be September. That means that the design was registered on the 15th September 1877. That represents the earliest date of manufacture. The FBRSS is the maker, EP means electroplated silver the rest could be Fenton Brothers, a Sheffielde Company, that’s a guess but I’m familiar with their silver marks. Hope this helps,
Tony