turret and one at the rear. The vehicle was very tall at 12 ft (3.5 m) and performance was poor. Due to the lack of armour plate, corrugated (manganese) plating was used in the expectation it would deflect bullets. The crew of eight included one gunner who had to lie on a mattress on top of the engine to fire his Bren gun. The tanks were constructed without the use of any formal plans or blueprints. Working from an American postcard depicting the conversion of a tractor to a 'tractor-tank', Bob Semple and TG Beck (Christchurch District Works Engineer), improvised the design of the tanks. Using resources available to Bob Semple as Minister of Public Works, work on the first tank commenced at the PWD's Temuka workshops in June 1940. The additional two were built at the NZR Addington Workshops. The first cost £5,902, and the second and third together cost £4,323, for a total cost of £10,225 (although the Army was only billed £3,414). The intention was to disperse the hulls at locations ready in case of a Japanese invasion at which point they would be mounted on tractors for use. The idea was discarded after the tanks attracted public ridicule; however, Bob Semple stood by his design and even stated "I don’t see anyone else coming up with any better ideas." Handling and performance Due to the limitations of requirements and resources, the tank was a functional failure. By using a large tractor as a base, and bolting on a hastily designed and poorly constructed tank superstructure, the resultant tanks were inadequately armored, extremely heavy (20–25 ton), unstable, restricted by tractor gearing to slow speeds, and had to stop to change gears. Furthermore, due to the shape of the underlying tractor and undue vibrations, shooting from the tank was both difficult and inevitably inaccurate. These limitations have caused the Bob Semple Tank to frequently make lists of "Worst ever tanks". Final result In the end, due to their impracticality, the tanks were disposed of by the Army. They had been given Army serial numbers NZ6292 (held at Papakura) and NZ3494 & NZ3495 (held at Burnham). Only one went to the Pacific in 1944, after having its armor stripped. It is possible that the Bob Semple tank could have been potentially useful in battle, as it was planned to have a 37 mm anti-tank gun rather than the Bren