IFS despairs as it finds no party’s imaginary numbers add up

Institute for Fiscal Studies reluctantly takes manifesto pledges seriously as it delivers verdict on spending plans of big four parties

Pick a number. Any number. Now double it. Or divide it by three. Anything really. Imaginary numbers in party manifestos mean something very different to those taught in universities. Proper imaginary numbers are potentially useful; imaginary imaginary numbers are just politics.

Both Labour and the Conservatives have called out the Institute of Fiscal Studies (IFS) for political bias at various times over the years, so it is safe to assume the economics thinktank is about as independent as these kinds of organisations get. It certainly isn't afraid of the tasks that many others would perversely consider simultaneously both in the public good and entirely futile, which is why its top economists have spent the past week trying to work out whether the spending pledges of the four main parties stack up in any meaningful way.