Many sources claim that the main armament, a nose-mounted cannon, was a standard 57-millimetre 6-pounder gun. John Glanfield, in his history "The Devil's Chariots", states that it was a 75-millimetre or 13-pounder gun. A 6-pounder main gun for such a heavy machine would have meant half the main armament of contemporary vehicles. The preliminary design, for which partial blueprints are in the Albert Stern archive at King's College London, featured two six-pounders in sponsons either side of a bulbous nose equipped with no fewer than five machine guns. Each side had two machine-gun positions on the flanks, with two more at the rear (the original Foster drawings make this quite clear; the reproduction of the drawings in David Fletcher's book "British Tanks 1915–19" is cropped and makes the rear guns ambiguous in nature). Originally, the shell-proof tank was referred to simply as the Heavy Tank, then Foster's Battle Tank. Where the nickname 'Flying Elephant' came from no one knows for sure, though it was probably the result of the trunk-like nose gun, domed front, and enormous bulk combined with a traditional British lightheartedness.