Brexit or not? Five weeks to go and pollsters 'don't know'

By Guy Faulconbridge and Michael Holden LONDON (Reuters) - Just over five weeks before a referendum on whether Britain should stay in the European Union, the message from opinion polls is simple: It is impossible to predict how Britons will vote on June 23. Opinion pollsters that failed to forecast both Prime Minister David Cameron's unexpectedly decisive election victory and the result of Israel's election last year have so far painted contradictory pictures of British public opinion.