While there was a general move to a general purpose gun that was usable against both tanks and in supporting infantry, there was a need to put the 17 pdr into a tank for use against the enemy's heavy tanks. The Cruiser Mk VIII Challenger was a project to bring a 17 pdr tank into use to support the Cromwell cruiser tank. Delays led to it being outnumbered in use by the Sherman Firefly—but a derivative of Challenger was the more or less open-topped variant "Avenger", which was delayed until post war before entering service. A cut-down 17 pdr, the 77mmHV was used to equip the Comet tank in the last year of the war.