It was the equivalent of a V-sign cheerfully flashed at his critics. The day after his landslide election victory, Boris Johnson and his girlfriend Carrie Symonds dropped into a caviar-fuelled Christmas party in London hosted by former KGB agent Alexander Lebedev and his son Evgeny.

During the campaign Johnson had stubbornly refused to publish the Russia report, written by the last parliament’s intelligence and security committee.

Its contents have still not been revealed. But it is understood to examine the extent of Moscow influence on British politics – and the way in which the Russian elite has established a powerful lobby in the UK through lavish expenditure and networking.

Facebook Twitter Pinterest Boris Johnson and Carrie Symonds attend Evgeny Lebedev’s Christmas party a day after Johnson’s landslide election win. Photograph: GORC/GC Images

The Lebedev family insist that they are merely entrepreneurs and media proprietors. Nonetheless, the party – held to celebrate Alexander’s 60th birthday – was a practical demonstration of how extensive their connections are, stretching all the way to Downing Street.

Johnson was one of several top politicians who turned up to the event, held at the Lebedev family’s £6m stuccoed mansion overlooking Regent’s Park. Guests included David and Samantha Cameron and George Osborne, now a Lebedev employee as Evening Standard editor. From the Blairite left, Peter Mandelson and Tristram Hunt were also in attendance.

Others invited to the vodka and caviar birthday party included Mick Jagger, Princess Eugenie, the actors Matt Smith and Rosamund Pike, and the model Lily Cole. Comedians Eddie Izzard and David Baddiel, the artist Grayson Perry and sculptor Antony Gormley were also there. Missing this year was the mayor of London, Sadiq Khan.

Facebook Twitter Pinterest Johnson and Evgeny Lebedev at a charity event in 2009. Photograph: David M Benett/Getty Images

As grand as the list was, the newly elected prime minister’s presence – the night after his election win – was eye-catching. Johnson has long been a celebrity as well as a politician – but for a leader who promised to lead a “people’s government”, to rub shoulders with such an exclusive elite as one of his first public acts after victory might seem a little incongruous.

Jeremy Corbyn was invited, but didn’t attend. (The invite, for the record, shows a youthful Alexander holding a toddler Evgeny.) In the Labour leader’s absence the Lebedevs hired a Corbyn impersonator, who mingled with guests as they sipped Ruinart champagne and tucked into plates of caviar. There was also a Johnson lookalike, perhaps hired just in case the real prime minister didn’t show up.

Johnson’s decision to call in on the Lebedevs might be explained as an act of political homage. The Lebedevs own the Evening Standard. Over the summer the newspaper endorsed Johnson to succeed Theresa May. It backed him again last month as the best candidate to be prime minister, an opinion at odds with the left-leaning, Remain-backing Londoners who form its target audience.

Facebook Twitter Pinterest Johnson went to the champagne-fuelled Christmas party in London on 13 December hosted by former KGB agent Alexander Lebedev. Photograph: Alexander Nemenov/AFP via Getty Images

What lies behind the prime minister’s reluctance to publish the Russia report has yet to be explained. He has dismissed the suggestion of Kremlin interference in the EU referendum vote. And yet on a busy day laced with history, Johnson chose to celebrate with a foreign intelligence officer with the rank of a lieutenant colonel, who graduated from the KGB’s Red Banner Institute.

As a young spy Lebedev served with the KGB’s first directorate. During the late Thatcher years he worked at the Soviet embassy in London, not far from the office in Kensington High Street where the Standard is based today. In the 1990s Lebedev senior swapped cold war spying for banking. In 2009 he bought a majority share in the Standard.

That complicated history has never put Johnson off spending time with the family. As London mayor, Johnson made repeated trips to the Lebedevs’ luxurious palazzo in Ronti, Italy, and to Evgeny’s parties in London in 2010. He was one of an array of celebrities and actors who flew out to the villa for lavish weekends, complete with a Michelin-starred private chef and a dressing-up box filed with exotic costumes. Evgeny’s pet wolves – one of them called Boris – would pad around as the great and the good enjoyed themselves.

Sometimes Johnson took his wife Marina Wheeler, from whom he is now divorcing. But in April 2018, at the height of the crisis over the poisoning of Russian former spy Sergei Skripal, Johnson flew to Perugia on his own. He was foreign secretary. In a highly unusual move, he left his security detail behind. The following morning he was spotted queuing at the airport for a flight home, looking crumpled and hungover.

Facebook Twitter Pinterest Johnson, then foreign secretary, on his way back from a Lebedev party in a converted castle near Perugia in Italy. Photograph: Supplied

What was the purpose of the trip? Johnson won’t say. In September, Alexander Lebedev told the Guardian he wasn’t at the palazzo. Two months later, speaking at the Moscow launch of his memoir, Hunt the Banker, Lebedev said he did go to the villa. He didn’t meet Johnson there, he said, instead merely calling in to wish his son a happy birthday.

Guests portray Evgeny as a needy and even lonely figure, craving companionship, and happiest in his Italian home, away from the burdens of being a media owner. They suggest he doesn’t really get politics per se. But, they add, he enjoys the superficial side of mingling with powerful individuals.

Facebook Twitter Pinterest Johnson, then foreign secretary, on his way back from a Lebedev party in a converted castle near Perugia, in Italy, spotted looking crumpled and hungover. Photograph: Supplied

Newly arrived visitors are invited to make a Russian-style toast to Evgeny and to perform a ‘turn’ of some kind – a sketch or speech. A lot of drinking goes on, with vodka shots and a mood described by one guest as debauched. Invitees are sometimes stuck there for days, waiting for a lift back on Lebedev’s private jet.

Whether in London or Ronti, Lebedevs’ parties bring together two groups who rarely mingle: celebrities and politicians. One is glamorous, the other not so much; both are curious about each other. The mutual attraction partly explains why so many high-profile individuals accept Lebedev’s invitations.

But others say there is more. One celebrity who has attended the Lebedev parties in the past now declines, arguing “all of these parties seem like covers for meetings” where people can discreetly connect with politicians under the the guise of the event.

Facebook Twitter Pinterest Johnson socialises with Evgeny Lebedev at a party along with his sister Rachel Johnson. Photograph: Alan Davidson/REX/Shutterstock

“Evgeny sends cars and flies people around on private jets, he makes people feel important, and always serves tons and tons of caviar, which people love. And there’s usually a photographer there ensuring attendees will get a bit of press,” the celebrity added.

Regular attendees at the Lebedev parties have included the actors Ian McKellen, Keira Knightley, Joan Collins and Ralph Fiennes. One non-actor celebrity – who declined to be named – received an invite out of the blue. When he climbed on board Evgeny’s plane he found that he and the other guests had one thing in common: they were all famous.

Facebook Twitter Pinterest Evgeny Lebedev and Alexander Lebedev at the launch of Alexander’s book Hunt the Banker: The Confessions Of A Russian Ex-Oligarch. Photograph: David M Benett/Dave Benett/Getty Images

Evgeny’s A-list contacts book is in part due to the Standard’s theatre awards, which have run since 1955 and which he now co-hosts. He also enlists his journalists to pull in big names. His former fixers have included Sarah Sands, who edited the Standard and is now editor of BBC Radio 4’s Today programme, and Amol Rajan, the former Independent editor who is now the BBC’s media editor.

In Russia, Alexander Lebedev depicts himself as a semi-oppositionist and victim of official persecution. His bank has been raided, and he has supported the independent newspaper Novaya Gazeta.

In reality, however, he is on warm terms with the Kremlin. In 2014 he publicly supported Vladimir Putin’s annexation of Crimea, where Lebedev owns a hotel complex in the seaside resort of Alushta. In 2017 he staged a media symposium there. It was arranged – he told Russian state TV – to correct a false impression of Crimea put out by a “biased” western media.

Lebedev shared a panel at the conference with Maria Zakharova, Russia’s foreign ministry spokesperson. She was a guest at his recent Moscow book launch. Zakharova is a hardline exponent of Kremlin policy; last year she denied Russian involvement in the novichok poisoning of Sergei Skripal in Salisbury and suggested that Britain’s spy agencies had kidnapped him.

The Lebedevs say that their forays into the British media are altruistic, and have nothing to do with Moscow’s darker global agenda. Whatever their motives for bringing them together, their remarkably diverse collection of friends – from the British prime minister to senior Putin functionaries – add up to an environment in which gossip, intelligence and information can flow as freely as the champagne.

Alexander Lebedev was contacted for comment.