WHAT happens in Falkirk does not stay in Falkirk.

That would be one conclusion to draw from the decision of the GMB union to cut its funding to Labour by a cool million, a sum known at the time of the Ecclestone/tobacco advertising affair as a "Bernie" but which must now be rebranded a "Mili" after the increasingly beleaguered Labour leader. He likes his omnishambles, does Ed, but this one could be the end of him.

It may be unfair to suggest that the country's third largest union is taking up financial cudgels on behalf of Unite, the biggest, after the falling out over Falkirk. After all, what is a disagreement over one candidate selection process, even if the party leader does hurl allegations of rigging (allegations Unite denies) and calls in the cops? Families have these sorts of disputes all the time, and it would seem unduly pessimistic to think there will be further blood spilled among the brothers as a result. Pessimistic, but probably accurate.

Perhaps what should most concern Labour supporters is that the leadership did not see this coming. Despite Falkirk, despite Mr Miliband hastily announcing reforms aimed at putting pale pink water between the unions and the party, despite grumblings from the unions at the time, the leadership thought they had this matter under control. There was to be a special conference next year, and any reforms would likely not begin till after the 2015 General Election, for which the unions would be expected to pony up as usual. But now old Boxer the carthorse has kicked back, firmly aiming a shoe at Mr Miliband's posterior.

Yet the GMB is merely taking Mr Miliband at his word. The leader wanted trade union members to actively opt in to Labour membership rather than, at present, have part of their union dues handed over automatically. Estimating that this would apply to only 50,000 of its 420,000 members, the union cut its affiliation funds from £1.2 million to £150,000. Should other unions make similar calculations, the party could find itself short by upwards of £7m a year. That is a lot of billboards and election pamphlets. A lot of anxious Labour MPs in marginal seats.

Mr Miliband's suggested reforms to the union-party link were the result not of blue sky thinking but plain old grey panic of the kind once exercised by John Major. The Labour leader was being mocked by the Coalition over Falkirk and teased mercilessly at PMQs by David Cameron. Foreseeing more of this to come between now and the General Election, the leadership wanted a way to kick the row into the long grass, hence the plans for a special conference. The assumption was that the unions would put up with the snub because that is what they always do.

On paper it must have seemed a neat solution. Be seen to loosen the ties with the unions at the same time as building what all parties dream of: a mass membership of paying individuals big enough to look impressive but amorphous enough to be controllable. As for any shortfall in cash, the unions could be persuaded to make that up with sizeable donations as the General Election approached. There would be no major consequences, the leadership reckoned, because the unions need the party as much, if not more, than the party needs the unions. As we know too well in Scotland, arrogance, thy name is Labour.

It requires quite astonishing conceit on the part of Mr Miliband to believe that there will be a rush to join his party. His poll ratings are sinking ever closer to the Earth's core, yet he believes union members, given the opportunity, simply cannot wait to back him with their cash. This at a time when voters have rarely been more scunnered with politicians in general, and when Labour refuses to make any public spending pledges this side of a General Election.

Besides arrogance there is amnesia at work here too. Mr Miliband would not be where he is, and his brother would not be halfway across the world, without the unions. The GMB, for one, backed him then and it has given £4.5m to the party since. Like every other union, the GMB is entitled to wonder what it is getting for its money. If the answer is "insulted" then it is no surprise that it begins to contemplate spending its money elsewhere. There are other ways to exercise influence on policy, from Twitter campaigns to professional lobbying operations or in-house efforts. It has been a long time since Labour was the only mouthpiece in town for savvy unions.

Given their financial, social and electoral importance to Labour, it is hard to understand why any leader would go out of his way to pick a fight as Mr Miliband has done. But then he is only following a tradition of Labour leaders down the ages. The relationship between the party leadership and the unions has always been one of town mice and country mice. The latter set up the party because they wanted, understandably, to send more of their own working-class kind to Westminster (they still do). Labour leaders ever since have had cause and opportunity to squabble with their country cousins, but at heart they believed fundamentally that the unions were assets rather than liabilities, that Labour was a family of the working and middle classes or it was nothing.

Then came Tony Blair. One of his first acts as Labour leader, the scrapping of Clause 4, was not so much a reform of the party constitution as a coup d'etat. The town mice were in charge now. The rich were no longer the class enemy, they were potential party donors to be courted. Mr Blair saw being bashed by the unions as a badge of honour, as a sign he was doing something right and electorally popular. Mr Miliband's mistake is to believe Mr Blair's publicity. The unions' mistake was to believe Mr Miliband was different from Mr Blair. They thought they were backing the anti heir to Blair. In reality he has offered much of the same, bar a war and being in Downing Street.

And so to the seaside at Bournemouth next week for the TUC Congress. If Mr Miliband were as high in the polls as Mr Blair once was, the likelihood is that he would not be about to have sand kicked in his face. But here is a leader who, not for the first time, appears uncertain of himself, who changes with the weather. Missing in action for most of the summer, he starts the new political year by costing his party a million, with likely more to follow. He tried to exercise greater power over the unions. Instead he has been left more vulnerable to any demands they may wish to make. All this to appear tough in front of the Tories. Better to be mistaken for red than be politically dead, Ed.