Even with New Labour now in urgent need of a major bail-out from the unions simply to stay solvent, Gordon Brown has apparently decided that he has better things to do than attend next week’s GMB conference.

Most delegates will privately be relieved not to have to sit through the inert expanse of boilerplate, platitudes and waffle that passes for a prime ministerial speech on these occasions. But the arrogance of the snub is both palpable and somewhat distasteful.

Perhaps one of the reasons for Brown’s no show is that a call for disaffiliation from the Labour Party is on the GMB’s agenda. Meanwhile, the Communications Workers Union will discuss the issue at its annual get-together, also planned for next week. Smaller unions such as RMT and FBU are already out of the fold, of course.

Union involvement in politics – for over a century channelled exclusively through the Labour Party – could well see major change over the next few years, with ramifications that everyone interested in the future of working class organisation would do well to think through before acting precipitately.

This whole question is especially crucial for those engaged in various projects to build a new political formation to the left of Labour. Union backing is the only possible development that could give these outfits meaningful traction; without it, they will remain isolated utopians, with only the most minimal base in the class they claim to represent.

Of course, if the couple previously described as ‘the two wings of the labour movement’ stood before a divorce court, the unions would clearly have New Labour bang to rights for unreasonable behaviour. They have suffered 14 years of slights that no spouse would tolerate. But sociologically, the roots of the divergence were evident long before Blair and Brown arrived on the scene.

I haven’t got the figures in front of me, but if I remember correctly, back in the 1960s over 70% of the membership of TUC affiliates voted Labour. That statistic fell to below 50% in 1979, the year of Thatcher’s triumph, and has never since risen above the half-way mark.

Yet in 1984, the Conservatives passed legislation compelling unions to ballot on the principle of maintaining a political fund every ten years. To the surprise of the government and the trade union leadership alike, the move backfired; ordinary members of most unions do see the point of having a political voice, and have consistently voted accordingly.

It’s just that they are no longer unanimous that this voice should speak in favour of New Labour, which has taken little more than a decade to trash loyalties that took ten decades to build.

Even as a Labour Party member, I can understand why many activists feel angry. But the tactical question that the far left needs to ask itself is whether or not disaffiliation would work to its advantage.

The danger is that, in the absence of any credible alternative socialist pole of attractions, most unions would either drop out of politics altogether or at best back candidates on a pick-and-mix basis, perhaps even including Liberals and Tories. That would ultimately push the prospect of a new workers’ party even further away.

It’s true that a handful of general secretaries – Bob Crow and Mark Serwotka are the most obvious examples – are openly Marxist and personally would have no problem with the idea of backing an alternative to New Labour. But even the most leftwing union leaders are entirely conscious of the difficulty in taking their memberships with them.

Crow, for instance, was an individual member of the Socialist Labour Party, and stood his ground when Labour expelled RMT for allowing its Scottish region to affiliate to the Scottish Socialist Party.

But it is simultaneously notable and unsurprising that he knocked back George Galloway’s overtures prior to London elections. What could he or his union possibly have gained from signing up to such a vanity candidacy?

And although the PCS enjoys/is subject to – delete according to preference - a greater degree of Trotskyist influence than any other major union in Britain, its civil service composition still includes many on the right of the political spectrum. Any political activity beyond that which can be presented as directly in the members’ interest is effectively precluded.

Finally, it’s worth pointing out that the GMB and CWU disaffiliation calls are considered certain to fall. Meanwhile, RMT continues to sponsor 21 MPs. All of them are Labour MPs.

If SWP/Left List, Respect, the Campaign for a New Workers’ Party, the SSP or Solidarity are remotely serious about winning union support they will frankly have to raise their game. The persistence of five joke mini-parties will continue to meet the derision such fissiparousness richly deserves.