Below is a quote from Roy Hattersley, I think writing in the Guardian. Now Roy could never be accused of being a rabid lefty so it's worth reading.
"When I was a member of Labour's national executive, Tony Benn would make long speeches about the plot to transfer all power from party members to the parliamentary leadership. Neil Kinnock and I shook our heads in bewilderment and mumbled about the need for Tony to lie down in a darkened room. I now realise that, far from being demented, he was prescient. The prime minister no doubt congratulates himself that it has become virtually impossible for Labour party members who disagree with his policies to make nuisances of themselves at the annual conference. But the complaint that it is no longer possible to express dissent is why so many members have left the party. In the short term the changes guarantee a quiet life. But when the pendulum begins to swing there will be too few members with enough long-term loyalty to defend an increasingly unpopular government."