The prototype demonstrated that the design was a failure and this sole example produced was retained by the School of Tank Technology as a lesson to its students.

[3] The Valiant, under General Staff specification A38, began as a candidate for an assault tank, with the thickest armour on the lowest possible weight, for use in the Far East.

The largest point of commonality was the choice of engine, the 210 bhp (160 kW) General Motors 6004 two-stroke diesel, as used in later marks of Valentine.

The Officer in Charge decided to abandon the trials there and then as it was impossible and unsafe to continue, reporting that "in his view the entire project should be closed".

[3] There were also issues with weight distribution and the ground clearance of only 9 inches (23 cm), and by that point of the war there was no longer a need for the tank.

Power was doubled to cope with the weight, using the new and compact 400 bhp (300 kW) Rolls-Royce Meteorite engine (a cut-down V8 Meteor) and an improved transmission.

[3] The sole Valiant was retained by the School of Tank Technology, where students were treated to an inspection of it at the end of their course and invited to find fault.