Factbox - The legal challenge over who can trigger Britain's exit talks from EU

By Michael Holden and Kylie MacLellan LONDON (Reuters) - England's High Court is due to rule on Thursday on a challenge to the British government's right to start divorce proceedings from the European Union, lawyers in the case said. The case at London's High Court was about one simple question: who has the right to invoke Article 50 of the EU's 2009 Lisbon Treaty, the formal process by which Britain notifies the European Union of its intention to leave the bloc and kicking off two-years of nego