Led by the 'rank and file' committee, many of whom are blacklisted, finally after six months of protests, unofficial walkouts and now a threatened strike, Balfour Beatty - one of the 'Dirty 7' building companies - has pulled out of the BESNA contract which will cut electricians' and other skilled construction workers' wages by up to 35%.
This is a major victory for Unite, coming on the back of the reinstatement of Paddy Brennan, the suspended convenor in the Swindon Honda plant and forcing Unilever and Wincanton back to the negotiating table after strikes in recent weeks.
It should act as an inspiration to the union in the public sector and re-convince the leadership that Unite should join in the pensions strike on 28th March alongside the likes of PCS and NUT. Obviously, it will be a major boost to the pay talks in the NAECI/Blue Book trades.
There is no question that the turn of Unite, and particularly its organising department, to the sparks dispute has been a major factor in gaining this victory.
The dossier that has been compiled showed Balfours that there was a war of attrition coming their way and there would be no hiding place anywhere, as the support of the Teamsters in the USA this week and the longstanding assistance of the Australian ETU has shown.
However, without the rank and file sparks, this would have been merely a paper document. They have breathed life into the dossier.
Their incredible campaign has acted as a lever on the union and allowed the officers to make threats of future action against Balfours knowing that it would be backed up by the site workers.
If they had any doubts on this they were dispelled by the protest outside the ECA awards dinner in London on Wednesday, with traffic on Park Lane being stopped for a hour.
Of course, the successful legal victory yesterday on the second strike ballot was a crucial moment. The Socialist Party correctly raised the prospect of even the Tory judges ruling against Balfours, as they did against Serco Docklands in favour of the RMT union's ballot in March last year.
Blatantly outlawing strikes that have had large majorities in favour - 82% before Christmas and 67% more recently in the case of the Balfour Unite members - can legitimise unofficial action.
In any case, the weekly action of the rank and file made it clear to the employers that the action would continue even if they won in court.
Unite made a mistake in re-balloting in December without going to court but corrected it this month.
Balfours' retreat is a crucial breakthrough but we can't rest until all the remaining six companies follow suit.
Therefore the campaign must continue until a total victory is won. If necessary, strike ballots should be launched in all or at least one of these firms.
Also, correctly the union is targeting improving the Joint Industry Board agreement. We support the involvement of the rank and file committee in any such talks and regular reports back to meetings of construction workers.
This is a fantastic victory after a marathon campaign, headed by rank and file workers. Unite has shown exactly what an industrial union of its size can be - a powerful force that can improve the working lives of workers.
This should be shouted from the rooftops and be the starting point for a mass union organising campaign on the construction sites, involving the new layer of activists that have been the stalwarts of this struggle. The recruiting slogan should be 'Join the union that saves 35% of your wages!'