There is really only one thing Boris Johnson can do to stop the questions over his Downing Street flat

A complaint by an MP over the Downing Street flat is seen as inevitable by ministers

Surprisingly, some ministers loyal to Boris Johnson think privately his biggest problem is not his alleged remark he would rather see the “bodies pile high” than impose a third coronavirus lockdown, which he unconvincingly denies.

Instead, they are fretting about the unanswered questions about who paid initially for the redecoration of his Downing Street flat.

Today, the Electoral Commission watchdog launched a formal investigation into the issue, saying there are "reasonable grounds to suspect that an offence or offences may have occurred." Not news the PM would likely have relished hearing.

Number 10’s carefully worded statement that Johnson has paid in full deliberately avoids whether someone else footed the bill before he did.

For me, this conjured up an image of Downing Street officials working out how to try to defuse the story without telling a porkie. The spin doctors’ golden rule is: “we spin, but we don’t lie”, because they have no credibility with the media if they do. I recalled writing about Number 10’s words when Cherie Blair was embroiled in a controversy over the purchase of two flats in Bristol in 2002.

The affair caused a serious breach with civil servants who believed they issued inaccurate public statements after being misled by her, as she later admitted..

As today, there were lots of headlines with the pun “flat denial.” Johnson, like David Cameron before him, is adopting some of Tony Blair’s ideas such as a Downing Street delivery unit telling fibs is obviously one page of the Blair playbook he should avoid.

The L-word matters. MPs are not allowed to accuse another of telling a lie in the Commons chamber because (don’t laugh) they are all honourable members. Significantly, Labour now uses media interviews to accuse Johnson of lying about the refurbishment of the flat – a way of raising the stakes.

Indeed, ministers who regard themselves as Johnson allies worry his failure to register a possible £58,000 donation or loan he received last July within a month as required under the rules, could land him in trouble with Kathryn Stone, the parliamentary commissioner for standards.

A complaint by an MP over the flat is seen by ministers as inevitable. I’m told Stone regards Johnson as “disrespectful” of the rules on registering MPs’ interests after his previous brushes with the system. A 2019 report by the Commons standards committee criticised Johnson’s “pattern of behaviour” after he failed to disclose a 20 per cent share in a property in Somerset shortly after making late registrations of his financial interests on no fewer than nine occasions.

The MPs said: “Mr Johnson is a senior and experienced member of the House, who could reasonably be expected both to understand the basic rules relating to registration of financial interests, and to set a good example to other members in obeying the rules.”

The committee gave him a slap on the wrist but warned ominously: “Should we conclude in future that Mr Johnson has committed any further breaches of the rules on registration, we will regard this as a matter which may call for more serious sanction.”

Even if he now comes clean about the flat redecoration, Johnson could face a punishment for running late again. Sanctions range from being ordered to apologise to even being suspended from the Commons. He is unlikely to face such a severe punishment for what he would doubtless portray as a technical slip-up caused by the pressures of leading the country through a pandemic-- an excuse likely to satisfy many voters.

Stone could issue a rebuke without referring the matter to the standards committee to consider a more serious punishment. However, she would be likely to put the ball in the committee’s court on the grounds that Johnson has form and that his failure to disclose a donation or loan for the flat was not “inadvertent.” (Stone is still investigating a complaint over the funding of Johnson’s holiday on the Caribbean island of Mustique 16 months ago).

Unlike on select committees, the Tories do not enjoy a majority on the standards committee, chaired by Labour MP Chris Bryant. Its four Tory MPs can be outvoted by the two Labour MPs, one SNP MP and six lay members, who have enjoyed full voting rights since 2019 to provide independent oversight of the MPs’ disciplinary process.

In theory, Johnson could use his huge majority of 80 to overturn any proposed punishment when it comes up for approval by the Commons. But that would be a humiliating act.

So it would be much better for Johnson to avoid that embarrassing scenario by revealing where the money for the flat refurb initially came from and doing something that never comes naturally to him – making a grovelling apology.