Great score!!
S Smith & Son was a noted clock/watch making company who also made car parts in London. That light would have been produced by Samuel Jr (the &Son part) as pop had died prior to the invention of the flashlight.
Yet when Jr inherited the company he kept the name the same. Flashlight museum shows a pair of focus beam lanterns from the 1920's.
Any 'glove catch' switch flashlight is a rare prize. But one made in England, by famous watchmaker Samuel Smith and a military issue? Now that is certainly special.
The American version was reportedly made around 1904 when Ever Ready was still shown in 2 words. Makes me wonder if Ever Ready had set up shop in London and produced this one for the Smiths so as to avoid a conflict with British military buying American flashlights?
It looks like a 3D cell size (which woulda been 3D cells wrapped in a toilet paper roll looking tube called a cell pack)
Tell us, is it a cardboard body or was it rubber?
Either way that is a super nice find.