“BRITAIN does not dream of some cosy, isolated existence on the fringes of the European Community,” asserted Margaret Thatcher in 1988. Now, increasingly, it does. Opinion polls show that most Britons are in favour of leaving the European Union. Baroness Thatcher’s Conservative Party, which took Britain into Europe four decades ago, is divided between those who long for an arm’s-length relationship and those who want to walk out. The second camp is swelling.