It is not only Russian oligarchs and multinational corporations who run to the ‘capitalist courts’ — as we used to call them on the left. Have an argument with Len McCluskey and you find that the leader of Unite is prepared to spend his money, or more likely his members’ hard-earned dues, on hiring the libel lawyers of Carter-Ruck at £550 an hour (plus expenses, of course).

Carter-Ruck can charge a little more than the minimum wage because its many wealthy clients know that its lawyers will push as hard as they possibly can to defend clients’ interests, as our spat with McCluskey showed.

Last week I published a brisk blogpost on The Spectator’s site in which I said that the Labour party should recognise that Unite was its enemy. The cliché that Labour and the unions were in a marriage was apt, I said: they fight all the time and don’t have sex. But few marriages survive adultery — and McCluskey’s eyes were always wandering.

Only last year he threatened to sever Unite’s links with Labour if the party’s policies did not comply with his wishes. He would put his union’s money behind a new workers’ party to the left of Labour instead. Perhaps he could take Unite-sponsored MPs with him, I speculated. After all, Unite has attempted at least once to use its influence to place its men and women in parliament; in Falkirk, a Labour party investigation said there was ‘no doubt’ that Unite had recruited party members in an effort to ‘manipulate’ the selection of a parliamentary candidate.

Meanwhile, in Tower Hamlets in the East End of London last month, McCluskey’s sidekick Andrew Murray announced, after an election court had disbarred the mayor Lutfur Rahman for electoral fraud, that Unite was ‘proud’ to support Rahman.

I would like you to take a breath and reflect that the Tower Hamlets episode illustrates to perfection the decadence of parts of the British left. There is a comprehensible left-wing case for a new socialist party. There are times when I might even vote for one — although I am not sure how many others would. But Rahman fought the Labour party in the East End by exploiting racial and religious division, in a manner leftists would rightly denounce if a white Ukip politician were to do the same. Rahman directed public money to Bangladeshis who were likely to vote for him, Judge Richard Mawrey found. He even diverted funds meant for the Alzheimer’s Society. Not content with that, Rahman and his associates bribed Asian TV stations to give him favourable coverage. He persuaded clerics to instruct their poor and credulous followers that it was an Islamic duty to vote for him, and to warn them that if they did not they would be siding with their Islamophobic enemies.

In other words, Rahman engaged in racial profiling, the exploitation of religious superstition for political advantage. He also perpetrated an electoral fraud, which denied the people of the East End their basic right to have their views represented in a fair election. Despite all of the above and more, Unite, Ken Livingstone and much of the left press excused him because Rahman claimed to be an enemy of the status quo.

Don’t be the put-upon wife, I told Labour. Dump the creep before the creep dumps you.

Instead of arguing back, McCluskey instructed his £550-an-hour libel lawyers to condemn our ‘highly defamatory’ portrayal of their client. I had wounded McCluskey. The poor little thing was ‘suffering from hurt and distress’ after the ‘extraordinary and grossly irresponsible’ decision of the editor to publish my piece.

McCluskey wanted an apology. Oh, and money. Not just damages but ‘aggravated damages’ and — lest we forgot — Carter-Ruck’s legal expenses, too. The Spectator’s lawyers told the Carter-Ruckers that their demands were ‘absurd’, and they appear to have gone away. Absurd or not, they can succeed. Whenever I am up against bullies, I congratulate myself on joining the campaign for libel-law reform. Thanks to its fine work, writers can finally express their ‘honest opinion’. Or rather some writers can. I am lucky to work for newspapers, which can afford to fight. Unite’s lawyers have also menaced a political website which offended McCluskey. Such websites cannot think of fighting libel cases and this sort of bullying therefore achieves its purpose of shutting down criticism.

Demands to censor can be a sign of strength. The magnate exercises his power by letting his opponents know that those who cross him will pay. But McCluskey’s threats betray his weakness. Britain’s trade unions are dying. According to the Office for National Statistics, in the 20 years between 1973 and 1992, an average of 7.8 million working days a year were lost because of strike action. In 2013, that figure fell to a mere 444,000 days. The unions have failed to recruit and offer help to the new working poor in the care, hospitality and service industries. Only 14 per cent of private–sector workers are trade union members. The future of those scraping a living in shopping centres and call centres is precarious and non-unionised.

McCluskey could form a new left-wing party, but the Greens have filled that space. Meanwhile, he must answer hard questions from his militants, who want to know why Unite needs a political fund at all. Like the syndicalists of the early 20th century, they want to give up on politics and concentrate on the ‘industrial struggle’. They have a point, and not just because zero-hours contracts and austerity give them much to struggle against. The tens of millions that Unite has given to the Labour party have not brought Labour to power. Indeed, Unite’s influence in making Ed Miliband Labour leader in 2010 ensured its defeat in 2015. McCluskey shows no sign of learning from his mistake, and seems ready to repeat his trick of pulling Labour away from the centre ground.

Behind all the threats and the bombast, his power is the precise opposite of what he believes it to be. All he can do is stop Labour winning.