Jennifer Arcuri first met Johnson in 2011, while he was London Mayor, and claims she “adored” him and had a sexual relationship with him.
Johnson had been married to his wife of 27 years at the time, Marina Wheeler - to whom he has four children.
So, who is Arcuri, what has she said of her relationship with the British Prime Minister - and how was she given “preferential treatment”? This is what you need to know.
Who is Jennifer Arcuri?
Arcuri is a 36-year-old Californian technology entrepreneur, who founded “ethical hacking” company Hacker House in 2016 and also organised London’s Innotech Summit, from 2012.
She studied politics at the University of Wisconsin-Madison, before studying theatre and film in New York and Paris. She briefly modelled and acted, before moving to London in 2011.
Arcuri organised the Innotech Summit in London, as well as being involved with Founders for Schools and also launched Playbox, a video social network for entrepreneurs.
Arcuri worked in the UK for three years, under an entrepreneur’s visa - having raised over £200,000 in funding for Innotech. It would later be disputed that some of this had come from her close relationships with Johnson.
Her Innotech Network was considered a meeting place for the tech industry and policymakers, such as Johnson. She also worked briefly with Sky News on a report about NHS funding for cyber-security.
In 2016, she founded Hacker House, which trains and advises on issues regarding tech-security.
Arcuri is now married to Matthew Hickey, the co-director of Hacker House, the pair welcomed a daughter in 2017.
In 2019, her company received a grant from the UK Department for Digital, Culture, Media and Sport Cyber Skills Immediate Impact Fund.
Did Boris Johnson grant her public money?
While living in the UK from 2011 to 2018, Arcuri had a close relationship with Johnson.
Though he insists this was strictly professional, Arcuri argues otherwise.
The Sunday Times has described the mayor as a regular visitor to her Shoreditch apartment, during her time in the UK.
In 2019, it emerged that Johnson had failed to declare his friendship with Arcuri when he awarded Innotech £10,000 from the mayoral fund in 2013, followed the next year by Arcuri receiving £15,000 from a government programme.
He also didn’t declare their personal relationship when he intervened to allow her onto three trade mission trips.
In September 2019, the Independent Office for Police Conduct (IOPC) launched an inquiry into his behaviour - the police involvement was due to his role as mayor also meaning he is also London's police and crime commissioner.
At the time, the London Assembly commenced its own investigation, but paused it at the IOPC's request in order to avoid overlap.
In May 2020, the IOPC announced that they would not proceed with a criminal investigation against the newly elected Prime Minister.
The investigation said: "While there was no evidence that Mr. Johnson influenced the payment of sponsorship monies or participation in trade missions, there was evidence to suggest that those officers making decisions about sponsorship monies and attendance on trade missions thought that there was a close relationship between Mr. Johnson and Ms. Arcuri, and this influenced their decision-making."
It also found there was a “close association” between Arcuri and Johnson, and there was evidence of an “intimate/sexual relationship” during the 2015 New York trade mission.
The Greater London Authority oversight committee is currently conducting its own investigation into Johnson’s behaviour.
Chair Len Duvall said the investigation "will consider whether Boris Johnson conducted himself in a way that’s expected from anyone in that position.”
Did Johnson have an affair with Arcuri?
On 28 March 2021, Arucri claimed Johnson was engaged in a four year sexual relationship with her from 2012 until 2016. She made the claims in a Sunday Mirror tell-all interview.
Ms Arcuri said Johnson visited her London flat hours before the opening of the 2012 London Paralympics, where she recalls the pair had their first sexual encounter.
This encounter took place some months after they met when she was a business student.
On first setting eyes on the London Mayor, she recalled: “He entered the room, his hair all dishevelled. That’s when I saw the first real magic of Boris Johnson.
"He’d turn the whole room into a bunch of howling schoolgirls. I made a beeline for the front of the line. I said, ‘Hello, my name is Jennifer, if you didn’t know me, now you do’.”
The pair reportedly swapped numbers, before meeting up when she volunteered to campaign for his 2012 mayoral re-election campaign.
According to Arcuri, there was an "immediate attraction on both sides, physical and intellectual".
Following the successful campaign, she told how he invited her for a private drink at the Tavistock Hotel in London’s Bloomsbury, which despite him asking her for £3.10 to buy a drink, left her feeling "enchanted" by him.
She reminisced of how “he showed up late, dishevelled and chaotic, he was biking - he came in with his helmet."
She said the pair also met for a meal in London, where she claims he “gave me a hug in front of everyone.”
Before adding: "It just felt so natural. We had red wine, I had a nicoise salad and he had fish and chips and then ate off my plate.
“He was very forthright. He said, ‘I can’t stop thinking about you, I want to date you, I really like you’.”
Ms Arcuri also claims Mr Johnson stroked her leg under the table, and told her "This is my city, I don’t care" when she raised concerns about them kissing in the street.
According to Arcuri, he "biked off in a huff" when she declined to go home with him.
But her refusals were shortlived, as she claims only a short while later, on 29 August 2012, the pair had sex just before the Paralympics ceremony.
Mr Johnson "didn’t want to leave", which she remembers as "the most bizarre experience".
Throughout the opening ceremony, he continued to text - according to Arcuri, who said it was “bizarre” and she watched him on television from her Shoreditch flat.
The relationship between the pair soon grew increasingly serious, as she told the newspaper: “We were in an intimate relationship for four years.
"I loved him, and with good cause. But the man I thought I knew doesn’t exist any more.”
The affair continued until 2016, with Arcuri saying she “did whatever I could find to convince myself I wasn’t falling for this man but, on some level, I knew.”
She also said she would send topless and intimate pictures of herself, whenever he said he missed her.
She said of one “arty” snap, that he described it as “enough to make a bishop kick through a stained-glass window”.
Are the pair still in contact?
Arcuri has now said she realises he isn’t the man she thought he was, and claimed he cast her aside as though she was a “gremlin” after she tried to contact him for advice on how to handle the media attention.
She told the Sunday Mirror: “It’s embarrassing. What a child. You can’t get on the phone and say, ‘Look Jen, this is crazy, welcome to politics’?
"He just took the most cowardly, wet noodle of approaches. This is who he is and it’s about time we recognised that.
“A great leader is charismatic, courageous and brave. None of these words I would use to describe Boris Johnson.”
No 10 has refused to comment on the allegations.
Following the IOPC’s findings in 2020, a spokesperson for Johnson said: “vexatious claims of impropriety in office were untrue and unfounded”.