“The manifesto has launched and it’s incredible,” Momentum announced to their activists today.

They’re right, and even the Institute for Fiscal Studies agrees.

Well, sort of. The actual words the IFS uses are “simply not credible”, which I’m pretty sure is the same thing.

Here is their verdict, which is very punchy for a normally rather beige institution:

Most of the proposals contained within the manifesto won’t come as a surprise. Nationalisations (included of the broadband network), embargoes on defence exports to Israel, increases in tax and borrowing, are all standard Corbynite fair.

What’s more interesting is the cost, and whether it will be an issue at this election in a way that it wasn’t in 2017.

Last time round, ConservativeHome was quick to point to the large bill and dubious hand-waving arithmetic which underpinned the Labour manifesto. Despite our best efforts, Labour was largely granted a free pass on the topic. The Chancellor was absent from the Conservative campaign, and Jeremy Corbyn’s claim that his manifesto was “fully costed” was accepted far too readily in the coverage of his proposals, given that it was not really true.

Just as this Labour manifesto repeats many of the ideas of the last one, so it features many of the same troubling fiscal flaws. First, look at the stuff they do give numbers for. The scale is even larger than 2017 – where they previously proposed £52 billion of tax rises, they’re now proposing over £82 billion – which is cause for concern in itself.

And these are the optimistic forecasts. While there are some efforts to account for behavioural change in response to higher taxes, they again seem to assume the only impact is in people trying to avoid tax – there is no provision for the fiscal harm done by reductions in growth sparked by, ooh I don’t know, the state hijacking businesses at arbitrary prices, chunks of pension funds being seized, or the arrival of a Government which thinks driving away wealth-creators is a virtue.

If those £82 billion of tax rises don’t materialise, of course, then Labour is still committing itself to £82 billion of extra spending. Fail to find it from the designated targets, and it’ll still be spent.

Then there are the elements of their proposals which are not costed. A “fully costed manifesto” apparently translates as one which refuses to provide costings for any capital spending, or any of the series of mass nationalisations Corbyn and McDonnell propose. We’re told there will be a £400 billion “National Transformation Fund”, which does not count on the balance sheet – it’ll be new debt, but that is something voters are meant to ignore.

We’re told that “taking companies into public ownership is fiscally neutral” because voila, now you own the asset. This seems to rely on the assumption that the asset’s value will be accounted as being equal to whatever a Labour Government pays for it – and McDonnell memorably will not say how much that would be, or even how the price would be calculated.

Worse, I can’t see any provision for the ongoing costs of running most of these newly nationalised industries. Even if you don’t mind the costs of buying them, building and renewing their fabric being waved away as hidden borrowing bills, surely it will cost some money for the state to actually control the entirety of the water, rail, energy and mail sectors? If so, this ‘costed manifesto’ doesn’t make any provision for it.

Might they just be relying on the nationalised industries being profitable under McDonnell’s tender stewardship? The same costing document refers to this as “public ownership of key industries that will…reduce the cost of living”, and Labour endlessly say one reason for nationalisation is to reduce utility bills and rail ticket prices. So their declared intent is to reduce the revenues of the operations after nationalisation, even before you consider the likely cost effects of their proposals to hand new powers to the unions and move to a four-day working week.

In case anyone might get a bit worried about all this, Labour have a clear pledge to assuage their concerns. There will be “no tax rises for 95% of taxpayers”. The burden for their plans will fall only on business and the top five per cent of workers, by which they mean anyone earning over £80,000.

That, too, is rather dubious. For a start, their “no tax rises” pledge only refers to Income Tax, National Insurance and VAT. And the pledge that they will only hammer people earning over £80,000 doesn’t apply to anyone who lives off the profits of a small business – Corporation Tax will rise, and the many people running small enterprises which have driven the economy and the jobs boom in recent years will be squeezed as a result.

And then there’s the question of whether that pledge to ‘only’ raise taxes on five per cent of people is even plausible. The clip I embedded above from the IFS suggests not. Here is that quote in full:

“The Labour manifesto suggests they want to raise £80 billion of tax revenue, and they suggest all of that will come from companies and people earning over £80,000 a year. That is simply not credible. You cannot raise that kind of money in our tax system without affecting individuals.”

So there you have it: a ‘costed’ manifesto which doesn’t provide costs for its most expensive items, an assumption that hugely complex nationalised industries won’t cost a penny to run at the same time as cutting their revenues, large tax rises which will hit the small businesses which are vital to the economy, and a pledge not to raise Income Tax on people which the IFS has instantly warned cannot be believed. and hundreds of billions in additional borrowing besides. And that’s before you put a price on the harm to growth, to jobs, to consumer and investor confidence, which would be done by a Government that does not respect property rights and boasts of envy as a virtue to be incorporated into the tax system.

Labour got away with dubious numbers, and damaging fiscal plans, in 2017. The Opposition worked hard to do so, and the Conservative campaign gave them an easier ride than they deserved. The early signs are that they’ll find it more difficult this time round: not only is the IFS vocal in challenging these bogus claims, but voters appear to be more sceptical of Corbyn’s promises.

To their credit, the Conservative campaign is also more on the front foot on the topic: sites like are being heavily promoted, and the smart move of registering is causing predictable heeby-jeebies from Labour’s outriders.

Nonetheless, the 2017 election is an ever-present cautionary tale. This is one of the Opposition’s greatest weaknesses – deservedly so – and they must not be let off the hook again.