The £1m man Questions over why Johnson took his donor to Ukraine

As he boarded the night train to Ukraine, Boris Johnson had the usual entourage of aides and bodyguards - plus the man who had given him £1m. Less than a year had passed since Johnson had accepted what is thought to be the largest donation ever to an individual MP. It was from Christopher Harborne, one of Britain's biggest and most private political donors.

- Tom Burgis

Harborne, whose millions helped bankroll Brexit, made the payment to a private company Johnson set up after resigning as prime minister. Now leaked files show that Johnson, a champion of Ukraine in office and since, was accompanied in September 2023 by his benefactor on a two-day visit that included meetings with top officials. What the files do not explain is why. And neither the former prime minister nor his backer will say.

The organisers of the high-level gathering in Kyiv say Harborne was registered as "adviser, Office of Boris Johnson". Harborne has wide expertise: a self-described "digital nomad", his holdings range from cryptocurrency and a wellness centre to jet fuel and stakes in at least three military contractors.

His only apparent connection to Ukraine is as the biggest shareholder in a British weapons manufacturer whose robots and drones are reportedly supplied to its armed forces.

The Boris Files, leaked documents from Johnson's private office, have exposed how he has sought to enrich himself since leaving office by sitting down with a Venezuelan despot and courting Mohammed bin Salman, the Saudi crown prince accused of ordering the murder of a journalist. The Ukrainian cause, by contrast, is "sacred" to Johnson, one political consultant says, a source of moral authority for a politician forced out of Downing Street amid scandal.

The leaked files raise questions about whether, even over Ukraine, he has blurred the lines between public service and moneymaking.

In an extraordinary statement to the Guardian when asked about his relationship with Harborne, Johnson said: "Your pathetic non-stories ... seem mostly to be derived from some illegal Russian hack job. You should be ashamed of yourselves."

Distributed Denial of Secrets (DDoS), the US-based transparency group that obtained the files, said it did not know their provenance.

Johnson added: "Why don't you just change your name to Pravda?