The Challenger Mk VIII Cruiser tank destroyer was based on the chassis of the A27 design. This newer design, called the A30, was intended to take on the heaviest of German armor after it was seen that the current crop of British tanks lacked the firepower to do so. This new design would fit an impressive 17-pounder main gun (76mm) and be fielded one per every three Cromwells. The A30 now became the Challenger Mk VIII Cruiser when going into production. Though utilizing the chassis of the A27, it was found that the A30 design required some customization to wield and fire the main gun and, as such, the hull was made larger in both length and width and a turret designed from scratch. Additionally, either track side received another road wheel to compensate for the added weight. As one can imagine, these changes directly effected the design's overall weight and the resulting turret gave the Challenger a high profile - making itself a larger target on any battlefield.
Additional standard armament included a Browning-type 7.62mm machine gun for self-defense. Crew accommodations amounted to five personnel and power was derived from a single Rolls-Royce brand Meteor engine of 600 horsepower. 42 total projectile rounds for the main gun could be carried onboard.
Once in production, the Challenger was in limited active use. Eventually, the design would give way to modified existing designs such as the Sherman-based "Firefly" of which many a British tank crew approved of. In the end, the Challenger Mk VIII Cruiser was nothing more than a stop-gap addition until more readily available and effective systems came online.