The British government is 'going all out for shale'. Those are the words of the Prime Minister about his plan to allow companies to try to extract shale gas from deep underground. It's a contrast to most European countries - many have banned it until they are convinced it can be done safely without damaging the water supply. Sarah Montague speaks to Britain's Energy and Climate Change secretary - the Liberal Democrat Ed Davey. If we want clean, green and affordable energy, what role should fracking have?(Picture: Ed Davey, Credit: Jeff J Mitchell/Getty Images)