The Spitfire Mk V certainly did have drop tank ability. The common size was a 90 Gallon "blister", aka "slipper" tank.
This type of tank was a flush-fitting drop tank that was rectangular, with a half-teardrop shaped profile(like a fat, inverted airfoil

). Not at all shaped like the German cylindrical/teardrop shaped tank the Spit 9 in AH currently uses...