This blog is primarily focused on psephology, not partisan comment. However, I must make a declaration of personal interest. I am a Labour Party member and I did vote in the leadership election. My preferred candidate (John McDonnell) pulled out and I gave my first preference to Diane Abbott; Ed Miliband got my second preference. This post is not about that.
This post is about that comment we've all heard from to time: "if David Miliband had won, Labour would be further ahead." Is it true? We can't possibly know, of course, but let's take the idea for a walk.
Labour had been in power for thirteen years and were deeply unpopular when they left. Normally when Labour leave office they struggle to get back in. After 1951 (an election when Labour won the popular vote, so no comparison with 2010 in that regard) Labour didn't get back in for 13 years. There are lots of possible reasons for this, but many point to disunity. Whether you blame the Gaitskellites or the Bevanites will depend on your political perspective, but we cannot escape the fact that Gaitskell failed to unite the party. When Callaghan lost in 1979, Labour remained out of power for 18 years. This election was more easily comparable with 2010, with Labour having changed leaders, become very unpopular and then kicked out. Callaghan was not as unpopular as Brown, of course! Again, there are many different versions of why Labour failed to win in 83 or the next two elections, but we cannot escape the fact that the party split! Michael Foot (and indeed, in a different way, Neil Kinnock) like Gaitskell before them failed to unite the party.
No Labour leaders unite the party. The Labour Party is a very broad church and is pretty-much impossible to unite. There are two approaches that have worked in Labour's post-war history. Blair's way has been pretty-much unique to Blair and to the very specific political circumstances of 1994. He imposed a "There Is No Alternative" vision onto a sceptical but desperate party and embraced and provoked disunity as a method of news management. He promised the party electoral success (and delivered) and the party went along with his changes to achieve this outcome. The other approach is the Attlee and Wilson (and Smith?) way. You might not be any wing's darling, but neither do you pick a fight with any wing. Neither wing sees your victory as their loss.
David Miliband was seen (rightly or wrongly, fairly or unfairly) as a Blairite. He had been the Blairite's challenger of choice against Brown (though he never actually challenged). The Blairite/Brownite split was always an odd one, not based on major ideological difference like the Gaitskellite/Bevanite split, but it was still real and bruising. If Balls had won, it would have been seen as the victory of the Brownites. Had David Miliband won it would have been the victory of the Blairites. Ed Miliband was the Wilson candidate. Associated with Brown (just as Wilson had been seen as close to Bevan) but independent enough from both camps to avoid the continuation of the old fights.
So, we can't possible know where we would be now had David Miliband won the leadership, but it is safe to assume that the old Blair/Brown rows would have rumbled on. Furthermore, the party would have found it harder to put the Iraq War behind them. Would the Cameron government have decided to let the Chilcot Report come out before the election, if Labour's leader was still arguing the Iraq War was the right thing to do? Possibly. Undoubtedly there would have been a lot of discussion and interest in whether David Miliband has really told Parliament and country everything he knew about extraordinary rendition.
Furthermore, David Miliband would have pursued a much clearer pro-austerity policy throughout this period. While some on Labour's right think this would have been successful, there is little psephological evidence for this. It certainly wouldn't have helped prevent Labour's problems in Scotland, and I think we would be seeing a much more potent threat from surging Greens if Labour had an economic policy less differentiated from that of the coalition.
We do not know what the result of the election will be but, given the historical precedents, the fact that Labour are in the fight, five years after a pretty serious drubbing, would suggest that Ed Miliband's leadership has been quite extraordinary in British political history and very likely more successful than his brother's could have been.