The first prototype of the Challenger tank was unveiled in 1942, as a carriage for the 17 pounder main gun. Based on the Cromwell, the massive block of the turret raised the profile of the tank to imposing... and vulnerable visibility, but this was seen as a compromise worth making for the fitting of the 17 pounder.
The Challenger went into service in the Guards Armoured, 11th Armoured and later the 7th Armoured Divisions, and after initial unpopularity, the speed of the tank won many over, though only 200 were produced by 1945, and went out of service shortly after.