We take a look at security in a post-Brexit world. Cooperation has always been key when dealing with other countries so what should happen now to make sure everyone is still protected? The EU External Affairs Sub-Committee has been holding a one-off evidence session to gather information on what the Common Foreign and Security Policy could be now. Dan Damon speaks to one of those advising the sub-committee, Professor Karen Smith from the LSE's Department of International Relations. The BBC's Political Correspondent Eleanor Garnier gives analysis and overview from Westminster. (IMAGE: British Prime Minister Theresa May (L) greets European Council President Donald Tusk outside 10 Downing street in central London on April 6 - JUSTIN TALLIS/AFP/Getty Images)