This is more for your information. So Atkin & Sons made other tools too? Looks like a horseshoe tool, my guess.
As Birmingham's largest and longest-lasting saw makers, Atkin&Sons stated in their trade directory entries (for what that's worth, ie not much) that they made many other tools than saws of all kinds. They certainly had a large and productive plane-making department, and took over several plane makers names. More credible is their catalogue frontispiece, reproduced in "British Planemakers", 3rd edition, p166, which states that they were manufacturers of Saws, files, planes, and edge-, joiners- and engineers tools. An even longer list of stated manufactures is from their 1885 catalogue (a copy of which is available to buy on Abebooks if anyone has a mere $471 to spare): Saws, Files, Planes, Edge Joiners & Engineers Tools, Braces & Bits, Tool Chests, Steel Toys, Gimlets, Augers, Rules, Skates, Machine & Chaff Knives. There is no chance that they made all these themselves, but it is very likely that as major suppliers their name would be on them.