Whatever happened to Jeremy Corbyn?  You know the controversial leader of the UK Labour Party who led the people’s revolt against Blairism and turned Labour into the largest mass membership party in western Europe.   Has he been accidentally buried in his allotment?  Is this year’s jam making proving more problematic?

Labour has been coming out with policy initiatives, like the £10 minimum wage – borrowed not entirely graciously from the Green Party.  Then there was the free school meals policy, borrowed from the SNP. I seem to remember Labour’s education spokesman, Iain Gray, criticising this policy because “the wealthy would benefit most”.   But fair do’s: there is policy innovation going on in Labour circles.  It’s just that there isn’t any leadership going on.  Labour offers no credible opposition to the government right now, and that means Labour policies aren’t taken seriously

There is no shortage of Labour factionalism going on. The fratricidal row over anti-semitism is something the party could ill afford at a time when it has lost much of its working class base, has split over Brexit and faces evisceration in the forthcoming council elections. There is a political tragedy taking place on the UK left, and it affects everyone in Scotland whether or not they support Labour.

The lack of an effective opposition in Westminster is allowing crucial decisions to be taken over Brexit without the Government and its legislation being held to account. A right-wing Eurosceptic faction,which barely represents the Conservative Party let alone the UK as a whole, has been allowed to run riot with the UK constitution and jeopardise our economic security.

The character and destiny of Britain is being altered as a result in ways that most civilised voters find abhorrent. In this once-tolerant country, immigration is now the defining issue in UK politics. The recent sabre-rattling over Gibraltar has revealed disturbing neo-imperialist passions released by Brexit. The project to turn Britain into a low-tax, low-regulation haven for exploitative capitalism is finally being realised.  Measures like the rape clause and the working age benefits freeze are being introduced with no serious opposition.  The welfare state is being wound backwards at an alarming rate.

It is the job of the opposition to challenge all this, and Labour is failing in this duty. The SNP group in Westminster may punch above its weight, but there is no way 56 MPs can perform the role of opposition in a legislature of 650. Yet Labour and the SNP could have united to provide an effective challenge to Brexit. After all, the Tories only had a 12-seat majority in the 2015 General Election, and there is almost certainly a pro-Remain majority in the Commons. Instead, Her Majesty’s Opposition has most recently been preoccupied with tearing itself apart over ludicrous allegations of anti-semitism.

This had little to do with hatred of Jewish people and everything to do with Labour’s passion for factionalism. No one seriously believes that Ken Livingstone is an anti-semite who believes that Jews collaborated with the Nazis in their own oppression. Mr Livingstone is a silly man – an attention seeker who thrives on making and defending controversial remarks, such as his claim that “Hitler supported Zionism before he went mad” on the Vanessa Feltz show two years ago. He did not say, as his critics claim, that “Hitler was a Zionist”, but the remark was sufficiently ambiguous for him to be under an obligation to undo the confusion and apologise for any offence.

A strong Labour leader would have waded into this dispute – as Tony Blair did into the row over clause 28 that split the Scottish Labour Party so disastrously in 2000 – and told a few home truths. No, Ken is not an anti-semite, but he should apologise. Yes, Jewish groups are offended, but the party believes in freedom of speech. Finally: both sides should damn well pipe down.

This is elementary party management. You don’t get fights like this breaking out in the SNP or the Conservatives because party discipline is intact. There are divisions on issues like the role of monarchy in the SNP, or over hard Brexit in the Tory Party, that could easily blow up into major media shouting matches. But passionate though those disagreements are, they are kept within the bounds of party unity. Both sides realise that they hang together or hang separately.

Regrettably, it seems that Labour would prefer to hang separately. The factions are so far apart that they would rather fight than pull together, even if it means mutually assured destruction. The right, and the anti-Corbynite grouping, believe that they have nothing to lose in stoking the fires of anti-semitism because they are doomed if they remain in the party under Mr Corbyn’s leadership. They believe they will either be deselected by local party memberships which have been taken over by Momentum, the pro-Corbyn grass roots movement, or that they will lose their seats at the next election as Labour is reduced to a rump by alienated voters.

For their part, Momentum supporters believe the right is using the Livingstone affair to demonise the left, destabilise the Labour leadership and effect a restoration of Blairite pro-market policies. They see Mr Livingstone as a cypher for Mr Corbyn, who has also been accused of tolerating anti-semitism. Momentum sees this as an existential fight not least because the anti-semitism smear was directed at its members when Jewish groups attacked remarks made by the former vice chair of Momentum ,Jackie Walker, last year.

It is of course quite in order for Jewish groups in and out of the Labour Party to express offence or to question whether Muslim and pro-Palestinian groups are insinuating anti-semitic memes into party debate. But it is up to the party leader to impose order on his party. Labour’s tragedy is that it has elected a leader in Jeremy who has transformed Labour into the largest mass membership political party in Europe, but who simply lacks authority over the party organisation.

Say what you like about Tony Blair, and I’ve said a very great deal about his many mistakes, but at least he had control over the party. Labour must find someone, preferably of a more radical disposition, who has the charisma, will and intellectual weight to save Labour from itself. And save Britain from hard Brexit.