I was looking at the Series 1 Spitfire, the one marked for Falkowski, as I am thinking of picking a couple up. I was curious about the squadron designator, PK, on the side of the plane. I've done some research into British squadrons but can't seem to find PK anywhere. Also, the Falkowski I find is Jan Falkowski, a Polish pilot who served in 303 Squadron. 303 flew Hurricanes, and were marked RF.

Is the model representing a later plane used by Falkowski? I can't find reference to him after October 1940

The Spitfire with PK squadron codes belonged to 315 Squadron (Polish). You can find some good introductory info here: http://en.wikipedia.org/wiki/No._315_Polish_Fighter_Squadron. This squadron was not activated until after the Battle of Britain. I believe that Flying Officer Jan Falkowski initially belonged to 315 Squadron, then later became commander of 303 Squadron. Hope this helps