In an era where everyone gets a mobile phone bill based on how much they use their phone, promising to freeze energy prices – as Miliband did – might get a cheer on Question Time. But such promises are just not credible, and voters know it. Jeremy Corbyn, with his complete rejection of the free market, makes Milband sound like a member of the Adam Smith Institute. A Corbyn-led Labour Party might sound great on Twitter. But it would plummet in the polls.