The idea of holding assets secretively in Monaco, Jersey, Switzerland or the Isle of Man has always held romantic appeal. But as regulators increasingly require transparent financial records, these tax havens are facing scrutiny.

Last month, Alistair Darling declared that Jersey, Guernsey and the Isle of Man - the UK's main offshore financial centres - could face economic reform and announced a review of their tax and revenue relationship with the UK. The Crown dependencies and overseas territories were luring customers with lower taxes "without contributing to the UK Exchequer", said Darling. "The British taxpayer cannot be expected to be the guarantor of last resort," he said.