Conservative Mayor of London Boris Johnson has said he has decided "after a huge amount of heartache" to campaign for Britain to leave the EU. He said the EU was eroding British sovereignty and PM David Cameron's EU reform deal would not bring about fundamental change of its membership. His decision pits him against Mr Cameron, who is calling for Britain to stay in a "reformed" EU. The prime minister says leaving the EU would be a "leap in the dark". The announcement by Mr Johnson, MP for Uxbridge and Ruislip South, follows intense speculation about which side he would back. BBC political editor Laura ... (full story)