my thanks again, of course. I have the main book on silver/gold marks for metalwork/flatware, but I notice that those books cater almost exclusively for the high value metal content pieces - and avoid the EPNS end of the market - they often include pewter. Manufacturers of EPNS (or at least those companies that plated such common items as flatware and small stands such as mine) are legion, and I don't recall seeing a book detailing these. I will investigate your link.
I have spent the last 20 years collecting the odd knife, spoon and fork whilst browsing the contents of boot sales - EPNS and Sheffield Plate - with the idea that when I retire I will find, hopefully, that I have collected something interesting (I have enough to open a cutlery shop). Coincidentally, last Sunday morning was obviously my 'EPNS morning', as you will see elsewhere