Most of them, that I know, did it for tax purposes. They started with just work visas, and kept working here. The US welcomed that.
Once they reached a certain income level, they were being charged huge taxes, in Britain.
One well known guitarist I know, was going to have to pay 90% of his income in taxes.
A well know singer I know, was put into a 78% tax bracket.
That’s the quickest way to drive off talent.
I know a Finnish musician who made the mistake of appearing on a very high profile tv show, before his visa was secured, and was told he had to leave the country. It’s been years and he’s never been able to get a visa.