Had to put this pix up after I saw it on a shipping site (they do aircraft too) because it's so good. I'm no expert on these things (and I know some of you guys are) so I'll simply copy the caption that went with it in here and you can ponder the facts as you see them. "Photograph of 41 Squadron Supermarine Spitfire F.XII aircraft based at RAF Friston in Sussex seen in flight over the South Downs. The aircraft pictured are: MB882/EB-B, MB858/EB-D, MB794/EB-H, MB840/EB-J, MB862/EB-E, MB843/EB-K and one other partially hidden. The mark XII was the first production Spitfire to be fitted with the more powerful Griffon engine and this necessitated a larger tail fin to counter the increased torque from the new engine. A retractable tailwheel was also added. The Spitfire's distinctive elliptical wing was also clipped at the outer edges to increase roll rate. A total of 100 Mark XIIs were built and they served with Nos 91 and 41 Squadrons."