This year, Tony Blair had to tell them that the agreement they had reached at the Labour policy forum at Warwick earlier in the year would stand.
This package of policies covered pensions and employment rights, including the right to the eight bank holidays not to be included in the four-weeks-guaranteed paid holiday. In all, the deal covered 56 specific points, and all the union leaders made it abundantly clear that if Alan Milburn had any thoughts of reneging on this deal for Labour's manifesto, then 'war' would have been declared.
The journalists covering the conference were keen to get the union bosses to trash Milburn's appointment, but while privately most union bosses think the new minister is a complete prat, they didn't see the need to say so publicly.
The Warwick deal was done by the 'Big Four' - Amicus, TGWU, Unison and the GMB. For the first time in living memory, the leaders of the most powerful unions are actually working together. On the Sunday before the conference starts, all the big guns hold their own press conferences, and the various spin doctors fight it out to get their union the most publicity. Not this year. They amazingly held a joint press briefing and it certainly had the effect of showing a strong united front.
One reason is because they are politically closer due to recent election results, in particular in Amicus with the defeat of Blair's 'favourite union leader' Sir Ken Jackson, by ex-communist Derek Simpson. But another reason for this unprecedented outbreak of unity is that the 'Big Four' think the TUC has become ineffective.
Part of this is blamed on the TUC leader. General secretary Brendan Barber hardly sets the world alight - I've already heard mutterings in Brighton about replacing him. That, though, would be a revolution in TUC terms because tradition has it that the deputy always takes over from the top man and Barber's deputy is a woman and a young one at that.
Nothing could give a clearer indication that the TUC has ditched its carthorse image than to have a young woman as its leader. Women represent more than half the workforce, yet even unions such as Unison that are predominantly female have a male leader. The unions may have got New Labour listening to them again, probably more for the cash they donate than ideology, but they still have a long way to go before the rest of the county listens.