I'm from the UK (England in particular) - I think most people from England would say they are British (sometimes depending on context / person / non-requirement for brevity: 'from the UK' instead).
Perhaps a higher proportion of non-English UK people would answer otherwise.
If I read that correctly, London seems to be the only place where a majority of people see themselves primarily as "British"?
It's nearly 10 years old, but I don't think things are going to have changed to make people feel substantially more "British", certainly not here in Scotland!
Both Scotland and England gave up their sovereign status when the Acts of Union were enacted, to form the United Kingdom of Great Britain.
Basically, Scotland, Wales, England, and Northern Ireland, are nations which comprise the United Kingdom of Great Britain and Northern Ireland, which is the sovereign state.
> Are not Scotland, Wales and England each countries though?
Sure, but in a sense where UK “countries” are a thing somewhat like US “states” (but somewhat less, in that neither is independent, but US states are notionally sovereign nevertheless.)
The UK is the entity which is a sovereign and independent entity.
https://en.wikipedia.org/wiki/Britain_(place_name)#Modern_us...
> The term Britain is widely used as a common name for the sovereign state of the United Kingdom, or UK for short.