The self-propelled guns that were built in the "tank destroyer" mould came about through the desire to field the QF 17 pounder anti-tank gun and simultaneous lack of suitable standard tanks to carry it. As a result, they were of a somewhat extemporized nature. Mounting the gun on the Valentine tank chassis in a fixed superstructure gave the Archer, looking somewhat like the light-chassis German Marder III in appearance. The 17 pounder was also used to re-equip the US-supplied M10 Tank Destroyer, replacing the American 3-inch gun to produce the 17pdr SP Achilles.