LONDON, ENGLAND - MARCH 23:  British Prime Minister David Cameron departs Number 10 Downing Street on March 23, 2016 in London, England. David Cameron chaired a second Cobra meeting today in the wake of yesterday's Brussels attacks in which 34 people were killed. He said that UK security had been stepped up in the wake of 'a very real terror threat' across Europe.  Home Secretary Theresa May will make a statement to the House of Commons following Prime Minister's Questions.  (Photo by Ben Pruchnie/Getty Images)