Any ideas?

Anyone got any idea as to what this came from? The person that gave it to me claims Spitfire and I have definitely found a coolant pipe on the Spitfire that it could be a part of but when I mentioned the markings on it back in Sept ’07 (25th to be precise) people said that the part numbers did not seem to be Spitfire. I suppose there is the possibilty of it being from an AFV of some sort.
Picture 4 shows the location of the plate which bears the markings as follows:
Top row: 54145/7715
Bottom row: Z16214 and a T in a circle the ends of the bars of the letter touching the edge of the circle
Far right end of the plate: a circle cantainingn what appears to be BS over 321
The piping appears to be about 1.75-2″ diameter.
Any light you folks can throw on the matter would be appreciated.