A powerful cross-party group of peers will seek today to begin a national debate on whether Britain should stay in the European Union by demanding a parliamentary investigation into the economic benefits of membership. Their action reflects a growing feeling in the House of Lords that withdrawal from the EU might be preferable to signing up to a new European constitution that would erode British sovereignty. It is also evidence of frustration among sceptical peers over the Government's refusal to grant a referendum on the constitution and their determination to pressure Tony Blair into granting one. The peers who want...