Not long after the Labour Party swept to power last summer, Charlie Mullins, a British entrepreneur who made his millions in plumbing, packed up and left. …He now splits his time between two sun-soaked destinations: Spain and Dubai. …Mullins…is part of a number of prominent, very rich people who are eyeing the exits or threatening to do so, including because of recent tax changes. …some of U.K.’s very richest residents are decamping to countries like Spain, Italy, Switzerland and the United Arab Emirates, places where taxes are lower or where the rich can pay a flat tax to shield their global income. …Alfie Best, founder of a company that operates residential and holiday parks, said he quit Britain for Monaco because of what he described as stifling tax and regulatory burdens. …Critics of the tax changes say it could amount to what British soccer enthusiasts call an “own goal.” According to the Institute for Fiscal Studies, the top 1 percent of U.K. income taxpayers pay 29 percent of all tax. If too many of those taxpayers leave, the government could end up with less, not more. …“Many of us may be uncomfortable with the very idea of a billionaire, but I think future generations will not thank us if we are blasé about the departure of people who create jobs,” [Watts] said.