As the new old proverb has it, you can gift the British left its best opportunities in a generation, but you can’t make it take advantage of them.

The hugely-publicised recent bust-ups in Momentum, complemented by Peter Tatchell’s spiteful and vindictive self-promotion stunt over the weekend, highlight an almost palpable death wish that seems to have gripped some quarters of our small world right now.

Jezza is no longer be all things to all leftists. After more than a year at the top, he remains stubbornly wedded to the political influences that shaped him as a politician.

In many ways that’s a strength, but nonetheless disappoints both those that counsel greater boldness, and those that would have him be things he has never been and cannot become.

Somehow oblivious to the perpetual assault Corbyn has faced from the right ever since September 2015, parts of the left – with their usual impeccable sense of timing – have decided to open up up a second front.

I am not particularly clear what some of the Marxist factions involved in the Momentum fight are trying to achieve. Neither, I suspect, are they. They seem hell-bent on fighting a war of manouevre, in a situation where a war of position would better surely be a better strategy.

Meanwhile, Tatchell’s petty charade will hardly have advanced the cause of electoral accommodation between Labour and the Greens, although that may well be by design.

In both cases participants start from a misunderstanding of what Corbynism is, and what it isn’t. For a start, it is not a revolutionary socialist project. Nor does it inherit the early twentieth century radical liberalism that largely elided into the Labour Party before world war two, and which provides an ideological framework for many human rights campaigners to this day.

Indeed, it represents more of a reversion to traditional workaday Labourism than either his boosters or his detractors would like to admit. Consider the actual content of the policy statements, which have yet to stray beyond such allotment plot hardy annuals as publicly owned utilities, building social housing, mildly redistributive but hardly punitive taxation, and old school Keynesian economics centred on infrastructure investment.

So far, so Harold Wilson; all good policies, all badly needed in Britain today, but not exactly a white knuckle ride for those who want to party like it’s 1917. The obvious rejoinder to the dissatisfied is, well, what did you expect?

I voted for Corbyn last year – with ‘no illusions’, as we used to say in Trot-speak – because I wanted to see a break with the disastrous direction of travel that lost Labour the general elections of 2010 and 2015.

As I have previously argued, a reversion to the Third Way would only guarantee certain electoral defeat. That is not to postulate that the Labour left will be able to articulate the ‘Labourism for the left behind’ now needed to secure success, but rather to insist it is the only section of the party even potentially capable of that intellectual task.

But an incidental by-product of Corbyn’s success is that the Marxist left now has a space in which to re-engage intelligently with mainstream politics, in a way it has not been able to do since the 1980s.

Hence the remarkable spectacle of a Labour leader arguing on a Sunday morning television slot last year explicitly that Marxists and Trotskyists were ‘welcome to join the Labour Party’.

Marxists could and should be engaged in constructively strengthening the Labour left in Constituency Labour Parties, where crucial battles are to be fought in the next year or so.

But that is too much like hard work. Instead, all eyes have alighted on Momentum, an organisation launched explicitly as a continuation of the first Corbyn leadership campaign.

To critics who complain that this renders it little more than a stage army under the total control of the evil Jon Lansman, the obvious response is: If you want something else instead, go build it.

That fact remains that Momentum has been remarkably generous in refusing to exclude non-Labour Party members. You would have thought a word of thanks would even be in order, if only for the chance to sell papers to huge numbers of enthusiastic new activists. But no.

I first met Peter Tatchell when canvassing for him as the Labour candidate in the infamous Bermondsey by-election in 1983. I’ve seen him regularly at political events ever since, and we are on cordial first name terms.

I have always admired his work on LGBT+ issues and human rights. His subsequent emergence as a high-profile member of the Green Party has done nothing to diminish that.

Actually, I even agree with him on the issue on the Syria issue. Aleppo really is the Guernica of our time, and I number among those who want to see Corbyn take a clearer stance on the slaughter.

But if all Tatchell really wanted was to extract a statement from Corbyn, he had many far more constructive ways of procuring one than derailing an official Labour event designed to highlight violence against women.

For a start, he could try picking up the phone. His name has sufficient weight to ensure that Corbyn would take the call. If that fails, the Daily Mail will surely accord him abundant space, presumably remunerating him at that publication’s legendary ample rates, to air his beefs.

None of the above should be read as a ‘Jeremy Corbyn, right or wrong’ stance. Frighteningly, Labour’s current poll standing is at its lowest since the year Tatchell and I first met. At just 25%, activist despondency is more than justified.

Last weekend also saw Diane Abbott express confidence that the Tories’ 17% lead can be closed in the next year. Great to hear it, but the leadership owes it to us to spell out what concrete steps it is going to take to achieve that outcome.

My point is rather this. No, Corbyn isn’t perfect. But every conceivable alternative will be worse for Labour as a whole, and worse for the left in particular. If you are going to be a critical supporter, put the emphasis on the support rather than the criticism.