This was a projected heavy tank developed (from July 1916) to withstand field gun fire by being constructed with frontal armour of 3in thickness and with side armour of 2in. The tracks were driven by two 105hp Daimler engines, mounted together on a common crankcase. As an aid to prevent bellying in soft ground, auxiliary twin tracks were fitted under the bottom rear half of the vehicle clearing the ground by 6in. When required they could be coupled to the main track and be brought into operation. The main armament, a 6pdr gun was carried in a large steel cupola mounted on the front of the vehicle, above the tracks. Designed by William Tritton, the vehicle was near completion at W. Foster and Company Ltd when the project was cancelled in December 1916 in favour of production of more tanks of the Mk I type. 90-100tons; crew 8; 6pdr gun plus 6 MG; armour 50-75mm; engine (2 Daimler-Foster) 210hp; 26.75ft x 9.84ft x 10ft.