Thanks for posting these interesting saws. I haven't seen a Williams before; google shows it would be Thomas Williams, Manufacturer of the celebrated "Pipe Brand". see 1905 catalogue, p5 and p7 for saws. http://www.herberthistory.co.uk/userdata/files/thomas_williams_catalogue_may_1905.pdf This catalogue lists address as 8 Smithfield, but your saw looks earlier and the business was established much earlier (they were at 14 Smithfield from 1822 per http://www.britishblades.com/forums/showthread.php?66508-T-Williams-Smithfield-London)
Thanks for the links. I was aware of the britishblades.com entry showing Thomas Williams at 106 Union St and 14 Smithfield in 1822 as a maker of surgical instruments and butchers tools. The 1905 catalogue is new to me and very interesting as it suggests the firm goes back to 1785. BSSM shows Williams at 14 Smithfield from circa 1841.
Good to have a reference to the firm's catalogue (complete with super-authentic blood stains...). It looks from the illustrations of the works as though this was a truly manufacturing firm, although it's likely that they didn't make absolutely everything they sold, because so few firms did, especially when they move into highly specialised fields like spring balances – and saws. Not sure I'd agree that the saw is much earlier than the mid 19th cent, although it's noticeable that such a comparatively short back saw is fitted with three screws very close together, which I think confirms it's a butcher's tool rather than a woodworker's (the big ones often had 4), even though in almost every other respect it's indistinguishable.
I thought I will share here as well. I got another Williams | 14 Smithfield 16" (15 1/2" actually) steel back then saw, which looks pretty old to me with stamp very near the toe of the back (normally you find most saws stamped somewhere in the middle). Initially I thought the saw might have been shortened?.. but it looks like back has not been altered/cut off with original chamfer. The plate is fixed with 4 split-nuts bolts (all of them probably replaced at some point, at least 2 of them are definitely smaller than the drilled holes). The handle is also much larger then most of the saws I've handled. From what I gather, the oversized handles more typical to earlier saws, although I got another 16" by "Long & Hawksley" with a larger handle and 3 small bolts. Just thought this saw might be of interest. p.s. I have not taken it apart and probably shouldn't, unless...
Congratulations Greyhound, You have an example (by the looks of it) of a four screw butchers saw as mentioned by Simon above. "although it's noticeable that such a comparatively short back saw is fitted with three screws very close together, which I think confirms it's a butcher's tool rather than a woodworker's (the big ones often had 4), even though in almost every other respect it's indistinguishable." BSSM has an 1884 listing of Williams - Metropolitan Cattle Market and Smithfield Works, Gee Street, St Lukes - Butchers Cutlers. And with a mark identical to yours dated as 1880. Fred