What would three million Hong Kong arrivals do to the UK economy?

In the days after the Brexit vote, Boris Johnson wrote for the Telegraph of his desire to re-open the UK to the world as “a truly global Britain”. The country sought a “new role”, he said, seeking to be “humane, compassionate, principled – to do good around the world, and to exploit growth markets to the full.” Much of this was pooh-poohed by Remainers characterising Brexit as an insular move, turning the nation’s back on the rest of the world. But this month the UK’s offer to allow almost three million people from Hong Kong to move to Britain and take citizenship shows the slogan has meaning. As far as “growth markets” go, it could also help turn Britain into just such an economy.