LONDON, ENGLAND - NOVEMBER 22:  A security guard walks past a giant Doctor Who poster at the 'Doctor Who 50th Celebration' event in the ExCeL centre on November 22, 2013 in London, England. The sold-out three day event in the ExCeL London convention centre celebrates 50 years of the show which has seen 11 actors play the role of Doctor Who and receives a worldwide cult following.  (Photo by Oli Scarff/Getty Images)