[Larry]

No wonder I failed to spot the 'serial number as I was not expecting to see it under the tailplane, as Martin has pointed out! Having said that though, there are plenty of examples of irregular markings in the RAF and even painting over the serial number as in Spitfire AZ-K was not 'by the book'. Another explanation is that the 'W3109' is a makers marking, put on the aircraft at the factory before it was painted according to Air Ministry requirements. Perhaps all Spitfires had their serial painted on or within them in this way! The fire from the crash could have burnt away the top camo paint.

W3109 was a Mk Vb with 54 Sqn and was shot down on 17.09.41 on Circus 95 to Marzingarbe (on French Belgium border). The pilot Sgt RA Overson was KIA and buried at Dunkirk.

54 Sqn used the codes KL at this time but these do not show in the photo. However as a Vb this aircraft would have had cannons and it looks like one cannon may be seen in the wing leading edge (on the right hand side of the second photo).

I'm going to stick my neck out and say it is W3109