The idea of fitting a 17-pounder gun into a Sherman tank had initially been rejected by the Ministry of Supply's Tank Decision Board. Although the British Army had made extensive use of the American-built Sherman tank, it was intended that a new generation of British tanks would replace it in the anti-tank role. First, there was the Cromwell tank, which was expected to use the Vickers high velocity 75 mm gun; this gun would have had superior anti-tank performance to the US 75 mm and 76 mm guns that were mounted in the Sherman. The second was the A30 Challenger, which was based on the Cromwell but with the even more powerful 17-pounder gun. These two tanks—and their successors, the Comet and the Centurion, which were already on the drawing board—were to replace the Sherman in British service, and so the prospect of diverting resources to mount the 17-pounder on the Sherman seemed undesirable.