A demonstrator for the "Leave" campaign holds a placard outside Houses of Parliament in London, U.K., on Wednesday, June 15, 2016. The Brexit battle took to London's River Thames as boats supporting the "Leave" and "Remain" campaigns jostled for space, while Irish rock star Bob Geldof harangued U.K. Independence Party leader Nigel Farage using a sound system. Photographer: Luke MacGregor/Bloomberg via Getty Images