Labour is on a sugar high with its bright ideas. What’s telling is the lack of detail

To a Tory social gathering last night of those who in more reverential times might have been called the great and good. A former Prime Minister, watching shadow chancellor John McDonnell, declares: “It was a mix of interesting and bats**t crazy”. Another grandee concedes, for all its mix of fungible calculations and thin respray of thwarted Eighties policies onto 2020 problems, “there was something to chew on”.

When they are not talking about Brexit, this is what concerns Conservatives as they look ahead to their own unhappy gathering next week. It’s a worry that while Jeremy Corbyn’s ideas are patchy and faulty, the Tories lack enough of their own to parry them.

A leading Tory Brexiteer with a background in financial services cites a growing City curiosity about McDonnell. She says: “It’s like having Mephistopheles to lunch — a frisson they enjoy”. According to one boss who rolled out the red tablecloth, he is “a courteous guest who swots up in the history of the firm”. His praise of Corbyn’s saintly tolerance of the evil press and brotherly hug at the opening of his speech at the Labour conference somehow suggested both solidarity and just a touch of benign condescension.

The Labour Party has a plan for sweeping change, consolidated by its now-dominant hard-Left ideology. It is bolstered in Liverpool by an aggrieved sense that it saw off a “coup” in 2016 (in reality, a half-baked affair led by a marginal MP who left zero trace on the internal debate) — and an internal tussle over anti-Semitism which has only convinced true believers that it is the victim of unjust scrutiny. The net result is the leadership is in charge while feeling permanently under siege from the “mainstream” media, the privatised utilities, the banks and now the Treasury (a new enemy on the list) to add to that elastic foe, the “Establishment”.

It uses its powerful centralising ideology to channel justified resentments about the causes of the financial crash and the division of material spoils since. Theresa May, before she fell into the slough of Brexit and election-failure despondency, also senses that this was a sensibility that needed addressing. But the review of her achievements on that score falls very short indeed. The space is now occupied by a Labour Party which has correctly sniffed frustration and ennui in the political air. It has verve and ideas — which is, alas, very different from having solutions that are capable of fulfilling its promise.

At its core, McDonnellism works by splitting the difference between old European social market solutions — which rely on political economies that do not change very much, whoever is in charge — and a stated intention to dismantle the underlying capitalism system (which has not worked terribly well when attempted.) A lack of detail points out where the weaknesses lie. The share ownership worker scheme is really a complicated cover for a dividend tax, since workers’ dividends would be annually capped at £500 — a lot less than many successful firms who pay dividends pay already.

The aim is to reach 10 per cent of equity split between the workers and the Government over 10 years (McElvoy’s law: do not trust anything a government says will happen over a decade). As a populist gesture, this sounds adept. Stagnation in real-term wages has left workers bitter about the distribution of gains. However, employment is more diverse then McDonnells’ Gosplan (the agency responsible for economic planning in the former Soviet Union) vision allows.

Many companies do not pay regular dividends and cannot be forced to do so. Employers can hold down wages to offset any losses, and those close to the 250-worker threshold might decide not to hire more people. Even as the pressure rises, major firms will be tempted to delist from the London Stock Exchange. Details, details. In Liverpool, such notions went into a big Magimix, blurred at high speed by the oomph of an excited base (and whatever else is lacking in Labour, a committed, uncritical grassroots is still on board).

The great wasted opportunity is that there is plenty to do to fix public-policy Britain that is not just about navigating Brexit. Even as an early advocate of academies, I can see they have fallen prey to poor management and rent-seeking conduct, which boosts the salaries of mediocre managers (not unlike the skewed rewards of some university vice-chancellors).

However, the tilt of the soft-Left towards poor solutions was on display in shadow education secretary Angela Rayner’s classic line that city academy expansion should be halted and nascent free schools stopped entirely, with no obvious logic as to what pupils would gain from that. We got the dead-eyed mantra that “every child should get a great education”. Alarmingly little attention goes into assessing what might be needed to make this happen. If we know one thing in public services, it is that simply removing money or support from one area does not automatically mean progress in another.

Where is the evidence that state schools before the decline of local authority rule under the Corbynites’ Great Satan, Blair, delivered excellence on a grand scale (or any scale at all)?

Rayner is clearly tacking Left in a run at the “second deputy” role dreamt up to get a woman near the leadership team. But she could make her mark more assertively by researching how best to take a scythe to some of the more absurd reward packages. Seeing as nearly half of all secondary pupils are in academies, all we got was a half-baked notion for the other half.

The gap between word and intention looms wide — as it does on how to create better jobs and fix the moral unfairnesses of an economy caught between austerity and technological change. A disorientated UK needs bold ideas from the Opposition. We got the sugar-high fizz from the McDonnell factory — it’s the nutrition we’re missing.

• Anne McElvoy is a senior editor at the Economist