| I believe the reason there appear to be so many more pre-99 was that they were all made in European spec with kmh clocks and then modifed by the importers when they arrived in the UK, so this is a total number off the production line.
After this time they left the factory in UK spec and you can therefore tell how many officially made their way into this country.
There are a couple of books by Ian Falloon that give all the numbers - check out by author on Amazon or something like that - they're a reasonable read. | 
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