Sweet irony of the decisive union vote in Labour leadership election‏

The votes of trade union Labour Party levy payers were decisive in Ed Milband’s success in the Labour leadership election, much to the chagrin of the right inside and outside of the labour movement who had anointed David Miliband as the New Labour continuity candidate:
http://www.spectator.co.uk/coffeehouse/6306398/the-unions-deliver-ed-miliband-to-the-throne.thtml
Over the past two decades there has been a concerted drive to marginalise and minimise affiliated trade union influence in Labour Party democratic processes. Notably in 1993 when one member one vote was introduced - in the face of opposition from most unions but supported by the COHSE & NUPE sections of newly formed UNISON - which led to the current electoral college for electing the Labour leader: http://www.guardian.co.uk/politics/1993/sep/30/labour.uk

How the affiliates voted

The Labour Party has published a breakdown of voting by affiliated organisations.
http://www2.labour.org.uk/leadership-affiliates

Although the turnout of UNISON Labour Link levy payers was disappointingly low at 6.7% (with only 28,142 of 419,142 casting votes), Ed Miliband received a larger number of those votes than his rivals.

As UNISON Active stated at the beginning of the voting period: ‘each affiliated member’s vote may not be worth much - 0.00000943 per cent - but Ed Miliband must receive an overwhelming majority of them to stand a chance of winning the election.’ http://unisonactive.blogspot.com/2010/09/labour-ballot-opens-today-unison-calls.html

Put simply, Ed Miliband would not be Labour leader without the support of GMB, UNISON and in particular Unite who mobilised a tremendous vote behind its recommendation. Today shows that the death of unions as a political force in Britain has been greatly exaggerated.