Younger brother Ed Miliband has narrowly won the five month contest to be the new leader of the UK Labour Party, defeating his older brother David by 50.65% to 49.35% of the vote.

The vote was close all the way, with MiliE (the shorthand adopted by UK papers) trailing 34.3% to 37.8% in the first round, when all five candidates faced the vote.

Indeed MiliE trailed MiliD all the way to the fourth and final round, and only prevailed when the third running candidate, Ed Balls, had been eliminated, and 16% vote distributed between the brothers.

Of the other candidates, Diane Abbott, the left wing member for Hackney, was eliminated first with 7.42%, and the centrist candidate Andy Burnham second with 10%.

The Labour leadership is voted in three ‘electorates’ – the parliamentary party (and European parliament Mps); the party membership; and trade union and a number of other affiliated groups voting as individuals. The percentage vote in each electorate (divided by a third – ie a 50% vote for you among MPS gives you a 16.67% vote, going to your total) is then added to give a total percentage vote.

As expected, MiliD led throughout in the MPs vote, gaining 14% to MiliE’s 11% in the first round, and holding a lead all the way through to round four (17.8% to 15.5%). However both brothers were neck and neck in the party and affiliates electorates, both gaining 14% of the party in round one, and MiliE enjoying a slight lead in the affiliates, 10% to 9%.

It was in the second and third rounds that MiliE gained his base, with Abbott’s and Burnham’s affiliates votes (4.1% in each case) going largely to MiliE.

These bumps gave him an affiliates lead of 16.7% to 10.8% going into the final round, and Ed Balls’s parliamentary and members vote went about two-thirds his way, pushing over the edge.

However, the narrow victory with a final precise result of:

David Miliband 49.35 (17.812, 18.135, 13.40)

Ed Miliband 50.65 (15.522, 15.198, 19.934)

leaves the Labour party with the leader a majority of MPs and party members did not want. The clear advantage is that MiliE has a mass base that MiliD clearly did not enjoy, but also has substantial bases of opposition in the party should he fail to perform.

MiliE’s victory was won, after a process of differentiation that saw him become increasingly critical of the New Labour brand of centre-right politics and cleave back to a more centre-left Labour message – the institution of a living wage, wealth taxes for infrastructure funding, caution on foreign wars, among others.

It’s a strategy, as MiliE campaign advisor Paul Smith told Crikey last week, based on intensive focus on the affiliates, a grassroots campaigning effort demanding a massive investment of time – especially compared to rounding up the MPs vote, which MiliD was always going to win. The MiliE camp argue that Labour will win by drawing disenchanted voters back into the process rather than fighting over swinging voters.

However, others argue that the affiliates vote leaves choice of the party leader in the hands of thousands of people who are not members of it. In the past this has included a large and active group in the further left. Today, it includes – in a number of professionalised unions – those who wouldn’t mind seeing Labour as a more visibly left wing party for tactical reasons.

It will also give the Tories ammunition to argue that the unions are still calling the shots in Labour, no matter how much it reaches out to the broader middle class.

The victory – which comes, as all such votes, on the eve of the party conference – also creates a problem with no good solution — what to do with David. The contest between actual brothers rather than mere bruvvers has generated a fantastic amount of intense energy, especially for the losing side. Though they are children of a leading marxist theorist, the Milis are part of the UK left-liberal Hampstead mafia, and David Miliband’s path to the leadership was all but assumed for the past three years.

For the fantastically ambitious, talented and arrogant man he is widely held to be, this is going to be hard yards. Furthermore his New Labour supporters have never ceased to see the older Labour forces which have constituted round MiliE as antediluvian thickheads who don’t get a changed world – and see their vanquishing as a prerequisite to eventual victory.

MiliE has tackled this head-on by inviting his brother to be chancellor, ie Treasurer – which will either draw on residual human connection to create a powerful team, or create a bloodbath psychodrama that makes the Blair/Brown decade long grudge match look like, I dunno, one of those soppy team handball games the Europeans like to play, I mean what’s that all about?

But in any case, the move will put the onus on David to get behind his brother – and to be damned as another Gordon Brown if he fails to.

And there is no greater insult in the contemporary Labour party.

Except of course for “another Tony Blair.”