Left winger Jeremy Corbyn is tipped to win Labour's leadership contest. How has he garnered so much support in a party which has spent the last two decades shaking off the vestiges of socialism? Corbyn's detractors blame far left entryism. But the far left in Britain is too small to account for the tens of thousands of Labour party members estimated to be supporting Corbyn. Reporter Mobeen Azhar talks to party members old and new in an attempt to find out what is behind the popular movement to return Labour to its socialist roots. Reporter: Mobeen Azhar Producer: Anna Meisel.