Pictured are a BULLERS LTD marked "Gisbourne Pattern" style Canadian Ry telegraph insulator and a BULLERS LTD, November 1915 dated, No.5 "Mill's Bomb" (named after it's inventor William Mills) grenade (empty, inert) with it's base plug showing the markings. Civilian manufacturers often fill government contracts for supplies during war when demands outstrip the military's usual sources. 2 examples from WW2 would be Corning (glass) and Ohio Brass (porcelain) who made the bodies for the MK 5 NM (non-metalic) anti-tank mine. These mines were undetectable to the electro magnetic sweeping devices. We are all (still) waiting on the development of glass/porcelain detectors.