Interesting write-up and quite enjoyed seeing your pictures. Question regarding the British "trench brooms." What would those have been? I'm unaware the British had any (short of the odd grouse-shooting subaltern who may have brought his double-barrel to France). Germans had the Luger with snail magazine, and of course the MP 18 SMG when that finally became available. Americans had some pump-action shotguns. Italian Arditi had some Beretta 1918 SMGs (the Villar Perosa was used really more like a Chauchat equivalent, vice as the SMG it really was). The Austrians produced (in small prototype numbers) the Hellriegel SMG. But I know of no British equivalent weapon (or French, for that matter).