An employee holds of a pint of ale above beer mats arguing for a Brexit at The Knights Templar pub, operated by JD Wetherspoon Plc, in this arranged photograph in London, U.K., on Wednesday, June 1, 2016. U.K. Prime Minister David Cameron said he'll hold a long-pledged referendum on the U.K.'s membership of the European Union on June 23. Photographer: Simon Dawson/Bloomberg via Getty Images