I suppose I should answer my own question concerning whether the left should now put their hopes in the Labour Party of the future.
Superficially one can find similarities with the ending of the Blair-Brown governments in 2010 and the close of the Wilson-Callaghan years in 1979. Most significant among them is that Labour in opposition tends to start off moving leftwards. But on closer examination there are two crucial differences between now and then.
First, unlike New Labour, the Labour Governments 1964-79 never abandoned social democracy. Wilson’s self-declared remit was left-leaning: to advance the well-being of working people within the post-war consensus and to be progressive in social, civic and personal affairs. In the latter, if not so much in the former, Labour chalked up significant success: abolition of the death penalty, legalisation of male homosexuality and abortion, lowering the age of majority to eighteen, etc. So in 1979 one could argue: “Labour is basically sound, but what we want is a more left-wing and progressive version of it. Let’s join and see what we can do”
The second crucial difference between now and then is that when Labour lost office in 1979, the left was never so strong in the constituency parties and in the trade unions. There was real hope that by mucking in the left could win through. In 2010 Diane Abbott, the token left-winger, is on the leadership ballot paper thanks only to self-interested charity of New Labour MPs. The moment behind her is tiny and marginal.
My conclusion is that the situation in 2010 is fundamentally different from the one in 1979. The stain of New Labour cannot be washed away in a few months. Socialists cannot be, and cannot be seen to be, the junior partners of the people who managed New Labour 1994-2010. The Labour Party will not change its spots soon. If the left has a future it is not with Balls, Burnham and the Miliband brothers.