Approximately 12 years out of production of the Carlton (in 2006) there was a reputed 9,675 of them still rolling around.
This is a little erroneous in so far as...
a) That would include all Carltons from 1978, so two/three Marks of Carlton (depending on your perspective whether it received a heavy facelift or a whole new Mark in the early 80s)
b) That includes a few hundred (at the time) Lotus Carltons, of course there was no Lotus [Vauxhall] Omega replacement
c) Omegas were in production for 9ish years, the Carlton/Omega A 6 years, plus the 8 years of the previous Marks
d) That lower Carlton figure does not include Senators, if you wanted a large top-spec Vauxhall in 2000 you bought an Omega Elite, in 1990 you bought a Senator
Its is suggested there to be around 4300 towns, villages and cities in Great Britain, that's a theoretical three per town, so probably not too far off the mark, when you consider cities will have a few more, villages will on average have none/the odd one. I know a guy who owns a Monza, and there's a guy in the same hamlet he lives in, also with a Monza, half a dozen houses away. Not in the club, doesn't know him, they've never really spoken, bizarre!