ENGLAND - The prospect of a hung Parliament would throw serious doubt over Brexit negotiations, due to begin in earnest in just 10 days. The BBC/Sky/ITV poll put the Conservatives on 314 seats, Labour on 266, the Scottish National Party on 34, Liberal Democrats on 14, Plaid Cymru on three and Greens on one. The EU's chief Brexit negotiator Michel Barnier has set June 19 as his favoured date for the start of talks, due to last around 14-18 months. Protracted negotiations over the formation of a new government - or even a second general election in 2017 - could put back the start of formal talks, squeezing even further the limited time available to forge a complex withdrawal agreement and a separate deal on future trade arrangements. Theresa May repeatedly urged voters to hand her a large majority so that she could go into talks in Brussels with the firm backing of the country and the House of Commons behind her. She warned that if she lost just six seats, she would no longer be Prime Minister, and an unprepared Jeremy Corbyn would go "naked and alone" to the negotiating table. Under the terms of Article 50 of the EU treaties, the two-year deadline for the UK to leave the union can be extended only with the agreement of the other 27 member states. It is unclear whether the letter informing the European Council of Britain's intention to quit can be revoked.