Hi Sean / guys,
Spitfire development is a big subject and a fasinating one also, i'm keen on learning more myself............so with the last Spitfire as a Mk24 - that leaves two not counted ? i'd be keen to know as would Sean & gregers, i'm sure.
Seafire's do total 8, as Mks 1, 2, 3, 15, 17, 45, 46 and 47 to make sense of both above replies.
Also its worth noting that often a Mk was released before its previous Mks as was the case with the 5 and 9, both hurried in to fend off German fighter aircraft and this meant development may be higher in earlier Mks - if that makes sense ! - (it did back in the 1940's thankfully)