The scramble to attract and retain the private banking business of the world’s wealthiest families has become that much more competitive amid the fall-out from the worst financial crisis in several generations.

According to the World Wealth Report, the annual survey compiled by Merrill Lynch and Capgemini, the global population of “high net worth individuals” fell by nearly 15 per cent in 2008, while their total wealth fell 20 per cent, leaving both measures at levels last seen at the end of 2005.