For a second time, Boris Johnson has been cleared of breaching the ministerial code over concerns about how he funded renovations to his Downing Street flat – though he faced opprobrium from his ethics adviser. The saga has lasted two years and spawned several investigations, most of which have now concluded. This is what we know so far.

What was Johnson accused of doing?

In February 2021, media reports surfaced that a Tory donor was funding renovations to the No 11 Downing Street flat Johnson shares with his wife, Carrie, and their children. Although prime ministers get £30,000 of public money a year to spruce up their official residence, the cost of the renovation reportedly exceeded that, rising as high as £200,000.

The Daily Mail said some additional payments were made through the Conservative party and had not been properly declared, so the idea of a trust was floated – like those that help pay for the upkeep of the prime minister’s countryside retreat, Chequers.

In March, Downing Street insisted Johnson had met all the costs personally. It later turned out others had originally footed the bill but he then came up with the money himself and the original payees were refunded.

Then in April, a leaked email came to light from a Tory peer, David Brownlow, to the co-chair of the Conservatives Ben Elliot, dated October 2020. Brownlow confirmed he was making a £15,000 donation, and another worth £58,000 “to cover the payments the party has already made on behalf of the soon to be formed Downing Street trust”.

Facing huge pressure, Johnson appointed a new ethics adviser, Christopher Geidt, to look into a potential breach of the ministerial code.

What did the first investigation find?

Lord Geidt’s inquiry said that to ensure credibility he had “tested the assertions” that “at no point” until the media reports first emerged did Johnson know either “the fact or the method” of money being paid to cover the refurbishment.

Although the work had started almost a year previously, Geidt said he had spoken directly to Johnson, and the prime minister said “he knew nothing about such payments until immediately prior to media reports in February 2021”. Geidt said Johnson had acted “unwisely”, but cleared him of breaching the ministerial code.

What about the second investigation?

While Geidt’s inquiry was under way, the Electoral Commission began its own in April, saying there were “reasonable grounds” to suspect an offence might have occurred. The watchdog published its findings in December 2021, saying the Conservatives had not reported Brownlow’s £58,000 donation and fining the party just over £17,000.

In its report, the commission confirmed that as early as 21 January 2020 – just a month after Johnson’s landslide election win – the supplier of the refurbishment provided a detailed proposal to No 10 about the work.

A curious piece of evidence also emerged from the commission’s findings: that Johnson messaged Brownlow on WhatsApp in November 2020 “asking him to authorise further, at that stage unspecified, refurbishment works on the residence”, and that Brownlow agreed and explained about the concept of the trust.

This appeared to suggest a discrepancy with Johnson’s original insistence to Geidt he “knew nothing” about the payments.

What happened then?

Unhappy he had not been given a key piece of evidence, Geidt spent December exchanging letters with Johnson to find out why, and whether it should alter the findings of his initial report.

Geidt eventually concluded, in letters released on Thursday, that he still believed Johnson had not broken the ministerial code. If he had, it could have set off a seriously damaging chain of events for the government. Usually, those who break the ministerial code are forced to resign – though Johnson has previously spared a cabinet colleague this fate.

The publication of the WhatsApp messages between Johnson and Brownlow, revealing the prime minister raised the issue of support for a “Great Exhibition 2” while requesting No 11 funds, means further questions are being asked, however.

What could happen next?

There could yet be another investigation, launched by the parliamentary standards commissioner, Kathryn Stone. She was awaiting the Electoral Commission report, and will also probably have wanted to see Geidt’s take before deciding whether to launch an inquiry of her own.

This could still be damaging to Johnson, given Stone has powers to recommend that sanctions be imposed on any MP found guilty of breaking the code of conduct, including for them to make an apology or be suspended from the Commons.