Vickers-Armstrong submitted the Mk VIII design to the War Office in September 1941, and in that same month the Tank Board of the War Office ordered 1,000 tanks, increased in November to 2,410. The Board hoped that production could commence in June 1942 at a rate of approximately 100 per month, to be produced by Metro-Cammell, a subsidiary of Vickers-Armstrong. It was also at this time that the tank was given the specification number A25 and given the name of Harry Hopkins Production began in June 1942 as expected, but immediately began to experience problems; these are not specified, but it appears that testing of the prototypes of the Mk VIII provided by Vickers-Armstrong raised a number of issues. A minute sent to the Prime Minister, Winston Churchill, in September from the Ministry of Supply stated that there would be delays in delivery of the tank due to developmental problems, and a report issued by the War Office in December stated that a number of modifications would be required before production could be continued; the front suspension system was singled out as requiring extensive modification. Problems were still being encountered in July 1943, with a report from the Fighting Vehicle Proving Establishment indicating that serious defects were still being found in the models being tested; the problems became so acute that trials of the Mk VIII were abandoned earlier than scheduled. By 31 August 1943 only six Mk VIII tanks had been produced, compared to a War Office requirement of 100 by the beginning of the year. Although the War Office persisted in retaining the design and issued an official requirement in November 1943 for 750 tanks to be built, only around 100 had been built when production officially ended in February 1945.