In a lot of executive level jobs part of your qualifications is your professional network. It’s going to be especially difficult to obtain a role like that in the UK when you’re competing with people who have strong networks going back to university and high school. Plus the sad fact is there is likely to be a certain amount of xenophobia that will work against you even if no one is willing to admit it. For a board appointing a CEO, the safe choice for them will always be to appoint someone they knew from their Cambridge days rather than appoint an immigrant with an accent. You’ll have to work 10 times harder to get to the same place.