Slightly OT, but a few years ago I met the head of Airmiles (before it became BA Miles). I thought they should make more of an effort to arrange link-ups with high end stores and the like for their Gold and Silver members.

She told me that the average income of a Gold or Silver British Airways card holder was surprisingly low. The bulk of people who fly on business are middle-management, with a surprisingly high proportion of engineers and other 'not too well paid' people. For every company chairman in F or J there are far, far more middle-rankers.

The same probably goes for Centurion. For every person who has it from purely personal spend, there are probably many who got it by running up corporate expenses - especially those who charge corporate flights to their personal cards.