Seems like the usual magazine definition of 'Britain' = largely England = mostly London.
The definition of diversity in British magazines usually fails includes the other countries within it, that's still no surprise in 2025.
I see they're mentioning a few regional things to keep themselves covered - but in terms of identity within the UK, anyone Scottish, Welsh etc is going to describe themselves as that first, before they're ever going to classify themselves as British.
'Bannau Brycheiniog' - shoehorn a bit of Welsh in there, because it's so definitively 'British', what percentage of Brits outside of Wales could pronounce it, without having to look it up? Never mind the rest of the world.