In early 2024, a vape lobbyist, a Vote Leave campaigner and a Vienna banker set out to persuade the rulers of an oil-rich Gulf emirate to give them a billion dollars. For the plan to work, leaked files suggest, they needed a frontman who had some pull with the sheikhs. So they hired Boris Johnson.

His time as the UK’s prime minister had ended less than two years earlier and he had left parliament. But Johnson retained relationships cultivated during his time in power. The Boris Files, a cache of documents seen by the Guardian, suggest he has sought to harness these relationships for self-enrichment.

The leaked files raise questions about whether Johnson broke ethics rules by lobbying a top foreign official to “secure his patronage” for a business venture that stood to make him millions.

In need of funding, Bia Advisory, a largely unknown “climate finance solutions” venture, hired the ex-PM as its “principal adviser”. The idea was to deploy Johnson – charismatic and well connected after his years as mayor of London, foreign secretary and prime minister – to open doors in the desert.

Since hosting the 2023 climate summit, the United Arab Emirates’ rulers have been keen to look green, channelling some of their immense fossil fuel revenues into sustainable projects. Abu Dhabi, the richest of the emirates, keeps a $300bn investment fund, Mubadala. Securing Mubadala’s backing was “the big prize”, Johnson’s staffer told his new partners. And from his time in Downing Street, Johnson knew the boss.

The staffer was Shelley Williams-Walker. She helped run Johnson’s Downing Street operation, then became one of three aides at the Office of Boris Johnson, a limited company. Like all former prime ministers, Johnson can claim £115,000 a year in taxpayer funds but may only use it for public duties.

His office’s role in his commercial activities raises questions about whether these funds, released under the public duty costs allowance (PDCA), have been misused. “This story is rubbish,” Johnson said. “The PDCA has been used entirely in accordance with the rules. The Guardian should change its name to Pravda.”

He did not respond to questions about Bia Advisory and his activities in Abu Dhabi.

Following the Guardian’s revelations this week that Johnson may have broken ethics rules over his dealings in Saudi Arabia and Venezuela, senior Labour and Liberal Democrat politicians have called for an investigation into his use of public funds.

Ex-ministers are prohibited from lobbying foreign government contacts they gained in office “for the purposes of securing business”. But in April 2024, while his aides were dealing with concerned inquires from an ethics watchdog about his role, Johnson boarded an Etihad Airways flight to Abu Dhabi.

Personal stake

The leaked documents, obtained by the transparency group Distributed Denial of Secrets (DDoS) and seen by the Guardian, indicate that Johnson was offered a personal stake in Bia Advisory.

The company was to be incorporated in the secretive jurisdiction of Guernsey. Documents suggest Johnson would receive 24% of the shares, with a further 20% for his aide Williams-Walker.

The remaining shares were to be split between two founders. One, Shem Baldeosingh, is a public affairs consultant who has most recently championed the vaping industry. The other, David Roach, is a PR man with political ambitions. He stood unsuccessfully for the Conservatives in the 2015 election, then ran the leave campaign’s central London operation in the Brexit referendum, according to his website. It was Roach who approached Johnson about the venture, according to an official filing by the ex-PM.

Although an Austrian banker was recruited, the firm had little by way of a track record in handling enormous sums of money. Yet, armed with Johnson, Bia’s pitch was audacious: to ask Abu Dhabi not only to let it manage €1bn (just over $1bn at the time), the documents suggest, but also for a grant of another €10m to cover initial costs.

This would indicate that the founders were putting in little if any of their own money while predicting 2.5% returns – potentially making them millions. But first they had to convince the Emiratis.

As prime minister, Johnson had hosted Khaldoon al-Mubarak at least three times at No 10. Best known in the UK as the chair of Manchester City, Mubarak attended an exclusive dinner for superstar financiers and industrialists during Johnson’s post-Brexit Global Investment Summit in 2021. And he was part of a delegation that accompanied Abu Dhabi’s authoritarian ruler, with whom Johnson inspected a guard of honour on the parade ground behind Downing Street.

Come 2024, it was time for Abu Dhabi to welcome Johnson. A state energy company part-owned by Mubadala paid him $350,000 for a speech at its green conference, the leaked files suggest. In advance, the head of the national oil company, who as chair of the 2023 climate summit in the UAE faced allegations of greenwashing, requested that the gifted orator praise his environmental leadership. Johnson appears to have obliged.

After the speech, the ex-PM was driven to Mubadala Tower, one of the glittering skyscrapers the emirs have raised above the desert. During a meeting with Mubarak he raised the Bia Advisory climate finance venture, the leaked files suggest. A draft of a letter prepared two months later for him to send Mubarak reads: “As I briefly alluded to when we met, I am now acting as principal adviser to Bia Advisory.”

Johnson appears to have lobbied a contact from his time in high office, contravening ethics rules designed to stop ex-ministers exploiting their public service. And the leaked files show the watchdog had not yet cleared him for the job. In fact, back in London, officials were raising concerns about Johnson’s dealings with foreign governments.

‘Mystified by the delay’

Johnson’s draft letter to Mubarak said: “As you know, a key part of my legacy as prime minister of the United Kingdom was coalescing world leaders around a series of concrete commitments at the Cop26 climate summit in 2021.”

But he made clear this was about business. He “would very much welcome the opportunity to engage with your team about what we hope might prove a [tempting] investment opportunity for Mubadala”.

The letter, however, was on hold. The Advisory Committee on Business Appointments (Acoba), the watchdog that vets ex-ministers’ money-making, had still not approved his Bia Advisory role. Johnson’s team was growing frustrated with the delay, the leaked files suggest.

Acoba told his office that because Johnson “proposes to contact foreign governments” the case had been referred to the foreign secretary’s team. This was David Cameron, Johnson’s old rival and a predecessor as prime minister, who had endured his own lobbying scandal in the Greensill affair.

In June 2024, with the letter to Mubarak still not sent, Williams-Walker, the Johnson aide who stood to take a stake in the venture, emailed the Acoba official handling the case to say Johnson had taken it up personally with Eric Pickles, the then head of the watchdog. “We are slightly mystified by the delay,” she wrote.

In the meantime, Williams-Walker told Bia’s founders, she had rewritten the letter “to make it more authentically Boris-y”.

“Once Acoba responds,” Bia Advisory’s Baldeosingh told Johnson’s aides, he hoped the former prime minister would send the letter to the Mubadala boss, “perhaps followed up with a personal message, to secure his patronage”.

None of those involved in the Bia Advisory venture nor Mubadala representatives responded to requests for comment. Neither did Williams-Walker.

The fate of the venture is not shown in the leaked files. Regardless of how it ended, the Guardian asked Johnson how much money he had made from his role. He did not answer.