The cliché is that it’s scandals about sex that tend to do for Tories, and scandals about money that do for their counterparts on the opposite benches. To give credit to the current generation of Tories, though, the last decade or so has seen, in this department, a feat of triangulation quite undreamed of by the likes of David Cameron or even Tony Blair.

The Conservatives have retained a creditably strong showing in the extra-marital nookie and unwanted sexual advances stakes; but my goodness, they haven’t half upped their game in financial sleaze.

Using ‘I was simply careless’ as your explanation for why you accidentally seem to have not paid several million pounds in tax won’t really cut it

All credit to Boris Johnson for captaining the team. The former prime minister’s arrangements with a series of well-connected sugar daddies continue to provide the fan service of a prestige Blu-Ray reissue of a classic film: Easter eggs, behind-the-scenes footage, making-of, blooper reel etc.

The latest ‘deleted scene’, lovingly restored for the retrospective Director’s Cut, is the one where, just weeks after helping secure a guarantee on an £800,000 personal loan for the PM, moneybags Richard Sharp gets the prime-ministerial endorsement to become Chairman of the BBC. No doubt he was the best candidate for the job, but it does look a bit absent-minded that neither man remembered to mention this apparent conflict of interest at the time.

But the current star of the show is Nadhim Zahawi. Admittedly, he was only Chancellor of the Exchequer for about fifteen minutes, during that magical few weeks last year when almost everyone got a turn at holding a Great Office of State, but Chancellor he was. And when you’re the man in charge of the entire nation’s tax system, the main quality you’re expected to demonstrate is – leaving aside for the moment such bagatelles as honesty and integrity — an understanding of, well, the tax system.

For most of us, no question, it’s a bit of a mystery. That’s why we struggle with our returns each year, and we employ accountants if we can afford to. I couldn’t tell you the difference between a marginal tax rate and an effective tax rate if you held a gun to my head. Honest mistakes are sometimes made, and the revenue is, within limits, more or less forgiving.

But if you’re the sort of acute, successful, balance-sheet-literate businessman who looks like a good fit for Chancellor, indeed actually becomes Chancellor, using ‘I was simply careless’ as your explanation for why you accidentally seem to have not paid several million pounds in tax won’t really cut it.

It especially won’t cut it when the way in which your ‘carelessness’ disposed your tax affairs looks for all the world like what others might describe as ‘very careful indeed’. You can accidentally forget to declare a bunch of share dividends or whatnot when you’re filling out a form; it’s harder to accidentally transfer your founding shares in a large company to a tax-efficient investment vehicle in Gibraltar owned by a trust controlled by your parents.

It’s even harder to sustain the defence of carelessness given the chain of events. When Zahawi became Chancellor, it’s reported that HMRC raised a red flag (apparently ignored by the PM and not mentioned to the prospective Chancellor) over his tax affairs. It was further reported that he had been under investigation by the Revenue, the National Crime Agency and the Serious Fraud Office – at which point Zahawi said he was unaware of any such investigation and stated categorically that his tax affairs were all ship-shape.

Well, perhaps he was and perhaps that’s how these things go. Still, you’d think in the circumstances that such reports might at least arouse his curiosity. He might want to actively find out whether he was under investigation by agencies with the power to put people in jail; and being, y’know, Chancellor of the Exchequer, it probably wouldn’t be all that hard to do so.

Rather, and again this is not the sort of thing one usually does in a fit of absentmindedness, his libel lawyers sent a succession of pompous threatening letters to Dan Neidle, the tax lawyer who first draw attention to Zahawi’s unconventional tax arrangements. They tried to insist these letters were confidential and that ‘serious consequences’ would attend their being made public. Neidle, to his credit, blew them a giant raspberry and published.

The carelessness continued. Zahawi claimed at first that he’d allocated his old dad founding shares in YouGov because he’d provided seed capital. Then when it was established that Zahawi Sr (in the form of the Balshore company controlled by a trust he owns) had invested £7,000 in YouGov, and that apparently two years into its life, the story changed. It was the invaluable business know-how he brought to the company that had helped earn him those shares. HMRC have since, apparently, taken issue with even this version of events – hence the reported £5 million repayment – though again the former Chancellor has been less than forthcoming on the details. We know Balshore sold those shares for £27million. Did some or all of that money find its way to Nadhim Zahawi? His settlement with HMRC certainly implies so, but the details are frustratingly murky. In December his minions are saying categorically that his tax affairs are all up to date; a month later he’s paying a large settlement to the taxman.

He has said firmly on the record: ‘I don’t benefit from an offshore trust.’ When the follow-up question (not an unreasonable one, since YouGov documents are reported to show that on at least one occasion Balshore gave him £99,000) was asked as to whether he had benefitted from an offshore trust, though, his representatives went silent. It’s all rummer than Michelle Mone’s daiquiri.

To be clear: there isn’t the faintest suggestion that this lacework of facts and inferences adds up to proof that Zahawi is a squirming, brass-necked old tax dodger who has been caught bang to rights and will do anything to avoid admitting it. But he’s in the unenviable position that it does rather look that way to the untrained eye. Come on, Nadhim: let’s see the hard facts that will disabuse us of this unfortunate impression.