Sorry Mark just a Civvy, I took it for granted it is what it is.
Memories of the Mk 5p are pretty good, I took lots of pictures, but sadly not of the census plate.
Then, I remembered there's a picture of similar plate in one of my many books.
On page 63 of Photo Sniper Chieftain by Robert Griffin, there's a clear picture of the census plate. It's exactly the same as the one I have, down to the Chieftain name in italics. The only difference is that the one in the picture been stamped with the Mk and history of the tank in the walk round.
Mine is a Virgin plate, probably destined for the Middle east but became a memento. I guess the bulk of the discarded stock went back into the smelting pot when the orders dried up.
This old girl was apparently in running condition and in pretty good condition.