All I know really is that the two area centres and Heathrow are band 5.
If only ...... Band 5 is only a dream in Prestwick Centre. Personally, I'd make Swanwick TC Band 6 (but only for those who do Heathrow and Gatwick functions
) and all other Area units or TC validations Band 5
OK, Thames could maybe be Band 4
A little bit tongue in cheek. But not entirely.