All I know is that I received a letter from Barclay's stating that I must close my account as I do not reside in the UK. If I don't close it they will do so on 31st August 2023.
So, the requirement is that I reside in the UK, which I don't and will not in the forseeable future.
I don't know whether this is a legal requirement, or just Barclay's deciding that it's better for their business.