Millionaires are on the increase in Britain, according to a study which found that one in 65 adults is now worth over seven figures, 41 percent more than five years ago. A rebound in house prices and stock markets following the 2007 global financial crisis has swelled their numbers by 212,000 to 715,000, a prosperity index published by Barclays said on Thursday. “The UK is becoming more prosperous … and every region is seeing a growth in these wealthy individuals,” said Akshaya Bhargava, chief executive of Barclays Wealth and Investment Management.