Imagine is probably John Lennon’s worst lyric. Against a sparse, effective musical backdrop (influenced by McCartney’s quasi-spiritual triptych Hey Jude, Let it Be and Maybe I’m Amazed), the rich Beatle John bleated on in 1971 about imagining a world in which there are no possessions. Somewhat at odds with the anti-market proselytising of Lennon’s most famous post-Beatles song is the awkward reality that the track was recorded in the studio built at Lennon and Yoko Ono’s then very grand house, Tittenhurst Park near Ascot. The Grade II listed building is set in 70 acres of grounds and was purchased with the proceeds of Lennon’s fortune made from the record industry, one of the most thoroughly capitalist businesses on earth.

It is appropriate then that the ludicrous John McDonnell, Shadow Chancellor of the Exchequer, should cite the ludicrous Imagine in his dotty conference speech at Labour conference today. Incidentally, Revolution – the b-side of Hey Jude – would have been no good as an alternative source of inspiration for McDonnell. In that powerhouse rock and roll song Lennon wrestles with whether or not to support the concept of revolutionary socialism and the fashion for political violence unleashed in 1968. McDonnell does not do such subtle self-doubt. Even when he is sitting in the same TV studio as a Tory former MP he called a stain on humanity who should be lynched, as was the case on Sunday on the Peston show, shamefully he would not apologise to Esther McVey. What a ghastly way to behave.

Today was McDonnell’s big moment, when we got a proper look at what he proposes to do “when” he is Chancellor. Labour and him and Corbyn advocates a return to a command and control economy, mass nationalisation and £500bn of extra spending for “investment.” Chris Leslie MP, a sensible Labour person no longer on the front-bench, described the implications as follows. The extra £500n would involve massive extra borrowing and probably a doubling of income tax and VAT.

As Andrew Lilico put it for his analysis of the McDonnell speech in the Telegraph:

“Perhaps the most transformative was a proposal that at the point of any change in ownership or winding down of a company, the workers would be given a first-refusal right to take the company over – effectively stripping every company owner of the right to dispose of her property as she pleases. If there were even the remotest prospect of Corbyn winning a General Election, many of these policies would seriously damage business investment just by being floated, let alone enacted. They are also morally outrageous. He wants effectively to confiscate all business property so as to share it with the workers, giving them control over whether companies can be sold off or wound down, and to demand that business be run such that it delivers a “clear benefit” to society as a whole, rather than being organised to the best benefit of those that own it and use it.”

There is a lot of talk around about treating the Corbynistas differently – more seriously – now that Corbyn has been re-elected with such a large mandate. But what is proposed, effectively the shutdown of the market economy and elimination of property rights, is mad, as history proves time and again. There must continue to be bias against stupidity and economic vandalism that would wreck Britain.

Lennon’s idealistic utopian posturing in Imagine was at least forgivable. His brain had narrowly avoided being fried irretrievably by LSD in 1966-67, and he was only saved by his inherent mental toughness and a tendency to lose interest in stimulants whenever addiction loomed. Simultaneously, and to his artistic detriment, he had fallen for Yoko Ono, a replacement Mother figure and conceptual artist in her own right who brought out the worst in Lennon, teaching him to avoid self-editing and self-criticism. He started to imagine that whatever he produced must be good because he had made it. Wrong.

But most of all, Imagine is forgivable because by the time he recorded it he had achieved so much with the Beatles. The breadth of his compositions from 1962 to 1969, the success of his magical partnership with McCartney and the iconoclastic, cool, confident figure he cut pre-1968, all mean his transgressions can be excused.

McDonnell in contrast has done nothing, other than agitate for the far left, support the Irish Republican cause and help orchestrate the destruction of the Labour party via the election of his friend Jeremy Corbyn.

There are only two related consolations. First, the entertainment value. McDonnell is unintentionally highly amusing in the way that he talks merrily about what he is going to do “when” he and “Jeremy” are in power, in government. The announcements they make are delusional and the assumption of victory is a hoot. The second consolation is that England – short of an apocalypse – will never vote for McDonnell and Corbyn.