While only the top 5 per cent of earners will experience higher personal income tax rates, higher corporation tax could impact the income of all households if hiring and spending plans fall in response.

So either Mr Corbyn’s “people’s champion” persona is just for show, or he has deliberately chosen to omit a key policy plank from a costed manifesto.

For better or worse?

Secondly – and maybe more importantly, given how Mr Mitterrand’s government was saved by a centrist finance minister – many business leaders fear the influence of the shadow chancellor.

John McDonnell is a self-declared Marxist. Unfortunately for analysts, judging just how deep Mr McDonnell’s Marxism really runs and how exactly he intends to turn the teachings of Das Kapital into policy is extremely difficult.

We tracked down a copy of his 2007 pamphlet, Another world is possible: a manifesto for 21st century socialism, in the British Library, expecting to find a cache of salacious quotes. They’re difficult to find.

It is a rather bland, if a little pious, stroll through the familiar arguments of latter day social democracy – the leftmost arguments, sure, but rarely radically so. He never defines what he means by capitalism or the market and seems to use them synonymously with corporate short-termism, which the economy would certainly benefit from eradicating.

The absence of any real policy is remarkable for a text pertaining to be a manifesto. It is vapid, not violent.

You may believe that the Labour manifesto is a Trojan Horse that will usher in widespread nationalisation, the state-directed allocation of capital and the undoing of economic liberalism.

But you could just as easily dismiss Messrs Corbyn and McDonnell’s stump rhetoric as just a half-baked attempt at progressivism by two left-leaning throwbacks, in which case it won’t be nearly as bad as some think.

There’s even the chance that, through the party’s economic stimulus, it could turn out for the better. 

Edward Smith is head of asset allocation research at Rathbones