Are they technically leaving if they are "non-domiciled"? That means their official home for tax purposes was never the UK. It also means the tax difference of them leaving is near zero surely?
Non-dom was a special tax regime whereby for 15 years they didnt look at your income from abroad provided it stayed abroad. It costs 30k from year 7 to stay in this regime. This was great for people who just want to come to the UK to work say in finance for a few years but don't want to move their inheritance regime or finances from other countries. It was much fairer than most people make it out to be since most oth…
Here's a list of prominent ones.
https://en.wikipedia.org/wiki/List_of_people_with_non-domici...
A Conservative MP who "inherited" the status.
A son of a British newspaper magnate that got it because his dad became a tax exile to France.
Hereditary peers in the House of Lords who were claiming to live abroad and so on
And many of the "other countries" in these cases are in fact tax havens like Monaco or Belize.