Ed Balls, the intellectual powerhouse behind the economics of the New Labour era, was once described as having a brain the size of a planet. He was treated with reverence as a result. Yet when he ran for the leadership of his party he came a poor third, losing to goofy Ed Miliband, a guy who had once served as his office junior. Similarly, one of the reasons Rishi Sunak became the candidate of choice in this Tory leadership race was because of his alleged super-smartness.

As a product of Winchester – the public school most associated in elite circles with outstanding mathematical and analytical brains – as well as Oxford, Goldman Sachs and various hedge funds, it stood to reason that Sunak was operating on a higher intellectual plane than were his opponents.

Sunak had every conceivable skill required to take apart complex problems, winnow the evidence and produce optimal strategies. It placed him way above that ridiculous Truss woman who made cringeworthy speeches about cheese imports and pork markets.

Well, as the Sunak campaign makes screeching u-turn after screeching u-turn and takes public positions which are, by turn, insufferably arrogant or obviously intellectually inconsistent, it turns out that the skills which made a lot of people a lot of money – including himself – are not wholly transferable to the political sphere. And that is to put it mildly.

A harsher version of that would be to say that Rishi Sunak is rubbish at politics. How else is one to regard a wannabe prime minister who apparently did not notice that at least half the Tory tribe is passionately opposed to the removal of Boris Johnson?

It seems likely that even among the half which acknowledges Johnson had to go, there is widespread regret at the way things panned out. There is a growing appreciation that only a figure untainted by the furore over his downfall can reunite the party.

Yet while Truss has pitched herself as the rueful loyalist, Sunak’s melodramatic resignation from the cabinet positioned him in the public eye as the key mover in the plot to defenestrate a leader elected by a landslide, both by his party members and then the public as a whole in a general election powered by his giant personality.

While Truss understood the appetite for tax cuts among the Conservative grassroots, Sunak imbibed the kool aid about hair-shirted fiscal responsibility being more persuasive in the middle of a cost-of-living crisis.

After lecturing Truss from such a lofty standpoint, even branding her approach ‘not moral…not Conservative’, he is, of course, now trying to grab some of her tax-cutting brownie points by promising to scrap VAT on domestic energy in the autumn.

Rishi Sunak and Liz Truss head-to-head at the BBC Leadership debate (Getty Images)

After going at her like a bull at a gate in their first head-to-head TV debate, Sunak discovered from looking at the post-match polling that his aggressive, spoilt-boy approach had gone down like the proverbial lead balloon. So he was notably more polite and restrained in the unfortunately truncated second TV debate last night. Unluckily for him, the ideal son-in-law branding cannot be re-embraced so easily as it was cast aside.

For a former hedgie, Sunak has been woefully non-adept at hedging his bets in the political sphere. His categorical claims – hardly backed up by evidence – that he is the only person who can beat Labour, or that Trussonomics will inevitably lead to electoral defeat must obviously bar him from serving in her cabinet.

Even the act of churning out disobliging quotes about Truss – that will make obvious future ammunition for Keir Starmer – is poor politics for him right now. This is well understood by Conservative activists to be a strategic blunder as well as the sign of someone whose vanity is out of control.

So he is on a path to lose – and lose badly – to Liz Truss. A 2016 Leaver contriving to be soundly beaten by a Remainer, not least because she has straightforwardly put her shoulder to the Brexit wheel, while he has allowed Treasury orthodoxy to lead him to rule out a hardball approach to forcing Brussels to make concessions on the Northern Ireland Protocol.

By her own skill in the trade of politics, acquired over ten years of unbroken ministerial office, Truss has managed to position herself both as the Boris Johnson loyalist and the candidate of change. Meanwhile, Sunak is the backstabber who is committing to deliver more of the same.

Truss had the material to go at him much harder – over his plotting against Johnson, his fixed penalty notice, his secret holding of a US green card while serving as chancellor, his fabulously wealthy wife enjoying non-dom status even as he was hiking tax for ordinary folk – and perhaps she would have done in extremis.

That fact that she has not needed to tells us how easily she has coped with his challenge in this final round of the contest. There are several weeks to go, but the ballot papers will land on doormats next week and the bookies are surely right that her victory is almost a done deal now.

As a fabulously wealthy figure with a base in America and widespread elite contacts across global financial services, Sunak now has many more fruitful options in business than he does in politics, where he has burned his bridges and turned himself into a pantomime villain.

Other political golden boys who ran into the sand have generally found a career change preferable to a long rebuild. Balls and Michael Portillo became television stars; Nick Clegg a California-based tech exec.

Likewise, the clever money will now be on Sunak doing something business-orientated quite soon and no doubt making a massive success of it.