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Only the early Spitfire MkI had the two blade propellor. By the begining of WW2, the aircraft were fitted with one of two types of three-bladed prop; the DeHavilland or the Rotol props.
Previous to this MAP had instructed Supermarine to fit the Rotol constant speed unit to ten Spitfires after first replacing the Merlin IIIs with a specially modified engine.
Not quite antoni. Your source(s) are somewhat inaccurate on some points.