It's true some times dream can come true. This arrived today. It's a 12" 12 TPI iron backed backsaw (carcass saw?). Made by KENYON the mark corresponds with one in the BSSM c.1780. The back tapers from 3/4" at the heel to 5/8" at the toe rounded top edge and chamfered lower edge. The plate is 1 3/4" at the heel tapering to 1 1/4 at the toe and .017" thick. It has no missing teeth, it's straight no deep pitting and is tight held in the back. The handle has a slightly more rounded boss than usual but obviously not fully "egg shaped". There are a couple small chips on the horns but nothing major. At some point someone has clearly tightened the split nuts (possibly replacements?) You see the this on the nuts on the back and file marks on the front don't go with the the grain of the wood. Thankfully the handle is very tight to the saw. It's very comfortable and didn't bind when I tested on a piece of pine strapping it definitely needs to be sharpened though. I never thought is actually get my hands on one let alone one in actual usuable condition. I'm a bit stunned tbh.
That's a lovely example, Gareth, so congratulations are due. I'd just like to note that of all the Kenyon dovetail saws I've looked at, the slightly longer, rounded boss on yours is the style most commonly seen, so I would consider it to be "the usual" style. My opinion only.