Prime Minister Gordon Brown has been left with a big headache over the government's plans to ratify a key European Union reform treaty following its rejection by Irish voters in a referendum.Opponents demanding a popular vote on the Lisbon Treaty here said that Ireland's "no" vote on the document meant Brown should now guild wars gold relent and call a referendum.Labour promised a referendum on the EU constitution in its 2005 general election manifesto, but the constitution was later rejected by French and Dutch voters.Brown argues that a vote is now unnecessary as the Lisbon wow gold Treaty, designed to streamline EU institutions after recent eastwards expansion, has no major implications for British sovereignty.