Who'd make the best PM, Cameron or Miliband? SDLP leader won't say #BBCNolan

Labour says the SDLP is its sister party. That's one of the main reasons given by the Labour Party for not standing in elections here. But listen to SDLP leader Dr Alasdair McDonnell talking to Mark Mardell on Radio Four's the World this Weekend yesterday. Stephen gets reaction from SDLP MP Mark Durkan