The A30 SP Avenger was a further development of the A30 Challenger, intended to resolve some of the design issues including the tall turret and limited mobility. No longer having the need for a fourth crewmember in the turret, the turret was able to be significantly shortened, and was also mounted on a lower superstructure. The turret was made open-top, but could be screened with armoured covers when necessary, providing the commander and loader with a full range of visibility. Additionally, return rollers were added to alleviate the track-throwing tendencies of the Challenger. However, by the time a prototype was completed, development of the vehicle had been deprioritised with the introduction of the 17-pdr-equipped M10 in favour of the Comet I, and it suffered in trials against the Archer and Alecto. The Avenger project was eventually dropped in 1950.

Introduced in Update 1.55 "Royal Armour" along with the initial British ground tree, the Avenger performs well in sniping and flanking roles. The powerful gun, along with good gun depression capabilities, allows it to make good use of ridgelines and unexpected locations, allowing easy shots on unsuspecting opponents. It also has great mobility (though not quite as capable as the Cromwell that it is based on), allowing it to be an effective flanker. However, note that Avenger's poor reverse speed and slow turret traverse, as well as weak armour, mean that attempting to battle opponents head-on will often end poorly.