The best politicians inspire, but part of their job is also to orientate: to survey an often confounding set of national circumstances, and tell us not just where we all are, but also what our position means and where we need to go next. A year on from that remarkable general election result, this is the challenge facing Jeremy Corbyn and the people at the top of the Labour party – a difficult but urgent task in increasingly trying times.

Just over a week ago, I was among the 3,000 or so people who spent an overcast Saturday in north London, at the celebration of politics and music branded Labour Live. Whatever its detractors claimed, it was a well-intentioned, creative event – but the sparse crowd and rather wearied atmosphere highlighted issues far beyond the organisers’ control.

It should stop framing policies as a return to the pre-Thatcher past. Tory free-marketry ought to be yesterday’s thing

Notwithstanding the passions that occasionally coursed around the site, the day reflected the inertia that has set in on both the right and left since last year’s election – and more specifically, Labour’s current lack of energy and big ideas, which was never more evident than when Corbyn took the main stage in the early evening and delivered his big speech.

It was essentially an oration I have heard many times before, in 2015, 2016 and 2017. Over an uneven, often apparently improvised half-hour with no discernible beginning, middle or end, he tumbled through homelessness, the need to “take the commodity out of education”, the mounting mental health crisis, and more. Brexit got the briefest of mentions, 20 minutes in. The tenor often sounded more despairing than optimistic. Potentially powerful lines were often mangled by verbal tics (“as a society” is a phrase that urgently needs to go). There was a lack of any real story about the current condition of Britain with the kind of coherence and emotional lift that might speak to the people who are yet to be convinced.

Play Video 0:26 'Where's Jeremy Corbyn?': anti-Brexit protesters chant in London – video

For sure, Labour has a set of entirely justified moral convictions. Thanks chiefly to the shadow chancellor, John McDonnell, it has the beginnings of an across-the-piece economic plan, and some very interesting ideas about making the country more equal from the roots up. But what the party doesn’t yet possess is an account of the last few turbulent years of British history, and any human, emotional story about what the country might look like if it gets to implement its programme. So when its big figures get to their punchlines, there are often only empty bromides. “We want to live in a world where there is decency, and above all, hope,” said Corbyn – which was very nice, but floated off into the air as soon as he had said it. The usual questions remained unanswered: What is the United Kingdom? Why should it hold together? Where has it been, and where is it going? And as well as all the despair, where are the spots of hope that point to a different kind of country?

Such, perhaps, are the perils of attempting to make political headway while maintaining a stubborn reticence about the biggest change the UK has faced since the second world war. Right now, politics begins and ends with Brexit: the current Labour habit of talking about the past, present and future as if leaving the EU is a tangential subplot simply doesn’t make sense. But that is what the leadership does, having concluded that, as the government tumbles into shambles after shambles, the best thing to do is sit the whole mess out and say as little as possible. It is some achievement that many leavers think Corbyn is a remainer, while remainers are split between those who think he is secretly one of them, and those who damn him as a hardcore Brexiteer. This in turn blurs into a wider sense of paralysis and confusion – not a good look for an opposition that may go into a general election much sooner than some people think.

In some alternative universe, there might be a Labour party that began making the case for single-market membership in the summer of 2016, and whose leader was the star speaker at the weekend’s People’s Vote march. But as evidenced by those irate chants of “Where’s Jeremy Corbyn?”, he and his allies resolutely believe that talk of another referendum is for the birds, and we have to leave the European Union – albeit with a secure deal, a transition period, a customs union, and maintained protections for workers’ rights and the environment. Given where Labour stands in relation to many of its own voters, that is a reasonable position. Indeed, when anti-Brexit protesters at Labour Live unfurled their “stop backing Brexit” banner during Corbyn’s speech, he should have thought on his feet, and restated it. Instead he kept stumm and some of his media outriders then tried to paint the disrupters as craven lackeys of the establishment (something proved, apparently, by the fact they have an office in Millbank Tower). Once again, what we missed was a clear, confident, consistent Labour narrative.

Facebook Twitter Pinterest ‘It would be easy to frame such things in terms of the message not getting through …’ John McDonell speaks at Labour Live. Photograph: Chris J Ratcliffe/Getty Images

The cleverest radicals tend to present their ideas as matters of modesty and common sense, so as to accomplish one of politics’ most overlooked imperatives: the necessity of reassurance. Beyond Brexit, that also ought to apply to large swathes of Labour policy. Whatever the factional tensions, one point needs to be made again and again: that as well as being a newly revived movement, Labour is also a political force steeped in knowledge and experience, and is successfully running all of England’s big cities. Maybe Corbyn and McDonnell are wary of comparisons with soggy European social democracy, but if their ambitious plans for regional investment banks are similar to what exists in Germany, that point ought to be made every time the policy is mentioned. If Corbyn wants to create a school system that isn’t built around incessant testing and league tables, he might point out that some of the most successful European countries offer lessons in how to do it.

There are big areas of policy – defence and foreign affairs, chiefly – that the left tends to ignore, but (and I’m being somewhat diplomatic here) which still sit between Labour and the voters it will need if it’s going to win. Perhaps most importantly, the party should stop framing its policies in terms of a return to the pre-Thatcher past – 1945 and all that – and start basing what it says in the future. It ought to be Tory free-marketry that feels like yesterday’s thing.

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If Labour does not yet have the collective capacity or inclination to do these things, the reason is not hard to identify. Beyond the union-funded Centre for Labour and Social Studies (aka Class), the Corbynites have no supportive thinktanks. The online noise surrounding their project tends to be about either the necessity of campaigning or factional battling, so questions of strategy and ideas tend to get lost. Put another way, the foundations of the new Labour party in Twitter and Facebook mean that many of its followers have become well-versed in the art of online shouting, but less used to discussing the challenges Labour faces. A little too much attention, perhaps, is paid to “melts”, centrist dads, and not enough to the difficult questions that political parties with their eyes on power always have to face.

Six weeks before Labour Live I was in Walsall, one of those large post-industrial, leave-voting towns – see also such places as Nuneaton, Derby, Mansfield and Dudley – where Labour seems to be falling behind. I watched the Tories gain council seats, and even Labour voters talked about the party in puzzled, stand-offish terms. Opinion pollsters may or may not be centrist stooges, but it also might be worth bearing in mind that a recent YouGov survey suggested that between January and May this year, there was a seven-point swing from Labour to the Tories among working-class voters. It would be easy to frame such things in terms of the message not getting through.

But in parts of the country a long way from north London, Labour’s predicament might come down to something much more fundamental: what is that message in the first place?

• John Harris is a Guardian columnist