The Corbyn surge has drawn into the Labour Party hundreds of thousands of people previously outside it.
It couldn't have done that unless, before the surge, there was enough oomph inside the Labour Party to get the Corbyn candidacy going (which wasn't easy: he was the fourth person approached to be a left candidate; he wasn't keen; enough soft-left MPs had to be pressured into nominating him that enough right-wingers would feel embarrassed about denying him the few extra nominations necessary to get on the ballot paper).
In my letter (Solidarity 376) about which Mark Osborn complains (Solidarity 377), I quoted reports I'd written from Labour Party conferences since 2010 showing a slight rise of oomph. Reports written by others on Young Labour events showed similar.
I, and the comrades who wrote the YL reports, were surprised even by the initial mobilisation to get a left candidate. We underestimated.
Mark is wrong in suggesting that Labour conferences appeared more lively because Labour leaders felt less need to carve them up. Under Ed Miliband the ruling-out of constituency proposals was worse than before 2007. One index of the increased liveliness was louder protests against carve-ups.
When Sean Matgamna (Solidarity 376) wrote that the unions getting Ed Miliband elected as Labour leader in 2010 was a first self-assertion by them, he hastened to indicate the limits: Miliband made only "timid, half-strangled" moves away from Blairism.
Colin Foster (Solidarity 375) had already written that "transforming the unions, too" is necessary, or otherwise "top union officials" will at the next stage stifle the movement.
Mark, however, writes that was not even assertion in the first case, or not really, because the unions failed to do what they have never done before — push forward a candidate of their very own — and instead backed one of the candidates emerging from the MPs.
That is like saying that rain is dry because it is not a deluge. 2010 and 2015 are the only times in the 115-year history of the Labour Party when the unions have got a leader elected contrary to the choice of the MPs. Always before they have passively accepted whomever the MPs chose.
Mark Osborn thinks Sean, and Colin, and I, all overestimated! It's like a sailor who dismisses his shipmates' mild warnings that some storm may be coming, and then when a storm breaks, much bigger than suggested, insists: "I admit there is a bit of rain now. But I still deny the clouds you saw!
My Theory says you were wrong, and my Theory is always right whatever you mere observers of facts say!"