How will the border between Northern Ireland and the Republic of Ireland be managed once the UK has left the EU? Sarah Montague asks Arlene Foster, Northern Ireland’s First Minister, how she will make sure Brexit does not mean a return to the divisions of the past.(Photo: First Minister of Northern Ireland Arlene Foster arrives for a meeting at 10 Downing St, London, 2016 in , England. Credit: Leon Neal/Getty Images)