[PeterA]

CBAF 318

On its own CBAF 318 just tells you it is the 318th component or sub assembly the Castle Bromwich Aeroplane Factory has built. This could be a wing, a flap, a tailplane, a fuselage. Mk I Spitfires were built by Supermarine, prefix 6S, or it could even be, but not quite, a Mk 22 as the complex constructing number system was started again from scratch.

30027 SHT7 Issue 14. Tells us considerably more. Vickers had a grouping system that goes back to the flying boat days. The fuselage or hull was group 27. So your data plate comes from a component from and including the firewall, cockpit/fuselage and the tail fin, remembering that the Spitfire was conceived with an integral fin prior to the joint at frame 19.

Type 300 is Mk I Spitfire and after Mk II successive Spitfires carried the appropriate type number - 361 for Mk IX etc.

Drawing number 30027 SHT7 Issue 14 is in fact the firewall and because of the CBAF construction number will be a Mk II. Issue 14 for this drawing is dated 10 July 1940 incorporating Modification number 76 which was Mk II specific.

So this plate is from the 318th firewall that CBAF built.

From the known data plates of surviving Spitfire P7350 we know that the cockpit number is CBAF 14 but the firewall is CBAF 15. Already it is out of sequence by ‘1’. A firewall that didn’t pass inspection or was rejected, a request by Supermarine, who would know, and they did not need to be sequential, just traceable on the inspection department record.

If we advance forward from the known data of the cockpit/fuselage of P7350 along the build line 304 (318-14) we arrive at P7851. On this basis and unknown deviation, from experience, we should therefore be looking at a Spitfire +/- 50 on P7851 or from say P7782 –P7918.

The only other known data plate tie-ups for Mk II's that I have are unknown location (Cockpit or firewall) plate for P7819 which is CBAF 302 and cockpit plate for P7973 which is CBAF 492. So certainly Spitfires in either side of P7819 would be worthy of close scrutiny with regard to final fate.

I may well give this a little more study and refine it, but that will have to do for the time being.

In the mean time if you could advise the date stamped on the plate it may well be useful for the movement card study.

PeterA