You can just make out the Lithgow stamp in front of the reinforce then the broad arrow with S in front of that hidden by the top wood I should say there are more stampings under the wood as suggested by the forumer's.
Nice rifle.

I to have a '16 No 1 MKIII Lithgow it still has the mag cut off and is a 5MD (Western Australianicon Military District) I sourced a matching 1916 5MD '07 Lithgow bayonet, a 5MD 1916 Lithgow scabbard and a Wrights black (Not blanco'ed) 1916 sling, these last 3 items well lets just say cost more than the rifle.