Steven Zaloga

To deal with this threat [the Panther] the British had developed a special mounting for the excellent 17pdr. antitank gun that could be crammed even into the small turret of the 75mm gun Sherman. this fined weapon was offered to the [US] Ordnance Dept. in the autumn of 1943, and was ignored. The Sherman with 17pdr. gun, called the Firefly, was issued to British and Commonwealth tank troop initially on the basis of one vehicle per troop, to deal more effectively with the new German tanks. The American tankers would not be so lucky.