Britain's Catherine, Duchess of Cambridge (L) talks with US First Lady Michelle Obama (R) is a reception room at Kensington Palace in London, April 22, 2016 where the Obamas were hosted for dinner. Barack Obama warned Britain against leaving the European Union on Friday, undercutting a key argument of eurosceptics by saying London would be "at the back of the queue" for a post-Brexit trade deal. / AFP / POOL / Dominic Lipinski (Photo credit should read DOMINIC LIPINSKI/AFP/Getty Images)
