It is difficult to see whether this will make any difference to the contest. If the vote were close or if Smith were followed by enthusiastic crowds to match Corbyn’s on his itinerary across the country, it might very well be a clincher. But that is not apparently the case. Party members, all but the baseline hundred thousand or so who were there before, have joined because everything about the old party offends them and everything about the political establishment needs changing. Maybe that includes Sadiq Khan, for although he was elected with a good majority as Mayor of London, the surge in his support was almost certainly more to do with Corbyn than it was to do with him. So his intervention will change few, if any, minds.