I HAVE NUMBERS!!
Had an e-mail from a contact with records by the above 2 model codes with details of those licensed and SORNed at the end of each quarter - the details on licensed goes back to q4 of 1994, the SORNed goes back to its introduction (IIRC) in q4 2007.
It would appear that the 'BX 16V' model code was barely used - it may well reflect the number of catalyst equipped cars, rather than a distinction between p1/p2.
I don't have total numbers registered, but back in q4 1994 there were 3430 'BX GTI 16V' licensed, and only 2 'BX 16V' - however, rather strange this, the maximum number of 'BX 16V' entries isn't reached until q4 1998, when a grand total of 9 are licensed
Of the 'BX GTI 16V' entries, the numbers drop VERY quickly. From that headline figure of 3430, we get down to 1517 by the end of 2000 (by which time there's 8 'BX 16V' entries, a year later and it's 1013/6, then 612/4.
The most up to date figures are for the end of q2 2010. At this time, there are:
Licensed:
BX GTI 16V - 72
BX 16V - 1
SORNed:
BX GTI 16V - 66
BX 16V - 1
So a fair guesstimate of numbers left in existence in the UK would be no more than ONE HUNDRED AND FORTY!!!!
I'm really shocked at that, but it really does point to why you don't see another as regularly as you might have done in years gone by. Certainly when I bought my old p2 in 2000 there were still almost 50% of the numbers registered still around. By my calculations, that figure is now around 4%!!