Almost 450 attendees at 2013 bash at Old Billingsgate Market sat at tables costing up to £12,000 each to rub shoulders with PM and cabinet ministers

Details of the web of bankers, businesspeople and lobbyists helping the Conservatives' bid for a second term in power have been exposed as the Guardian reveals key guests at last year’s secretive annual party fundraising dinner.

The 449 attendees at last year’s Thameside event on 24 June had a combined wealth in excess of £11bn, with elite diners sitting at tables costing up to £12,000 each to rub shoulders with David Cameron, Theresa May, Philip Hammond and Boris Johnson, as well as the secretaries of state for health, transport, culture and justice.

Six billionaires and 15 people with a personal wealth above £100m were present at the closed event at Old Billingsgate Market, including 73 financiers, 47 retail and property tycoons, 10 in oil, gas and mining and 19 working in public affairs and PR, documents seen by the Bureau of Investigative Journalism and the Guardian reveal.

Disclosure of last year’s guest list – which the party intended to remain private – comes just ahead of this year’s fundraiser, which will take place on Wednesday night at the Hurlingham private members’ club in west London.

The precise amount raised from the 2013 event cannot be quantified, but Electoral Commission filings show that since the ball those present have donated a total £5m, £1.1m of which was registered in the week after the event. Table sales raised at least £250,000, with the cheaper tickets going for £400 a time.

Theresa May, the home secretary

The main sponsor was Shore Capital, a Mayfair boutique investment bank led by Howard Shore, who has donated £450,000 to the Conservatives personally and through associated companies.

Shore booked three so-called “premier tables”, on one of which he hosted David and Samantha Cameron. Others on the prime minister’s tables included Nicolas Berggruen, an investor known as the “homeless billionaire” because he lives in hotels around the world; Darko Horvat, a Slovenian tycoon; and the property grandee Sir John Ritblat. In a statement, Shore’s company said: “Shore Capital supported the event and made a financial contribution as they believe that the Conservative party, led by the prime minister, are the best party to govern the country.”

One of the most surprising guests was Vladimir Putin’s judo partner, Vasily Shestakov, who was introduced to the prime minister. The Russian president’s key aide had been tasked with improving Russia’s reputation in the UK and the handshake was “to make the wheels go round”, a member of the Russian’s party said.

Boris Johnson, the mayor of London, shared a table with Andrei Borodin, an exiled Russian banker who is wanted by the Kremlin to face charges of “aggravated swindling” over an alleged £220m bank fraud, which he denies and claims is politically driven. Borodin said: “I participated in no conversation on policy or party funding issues, nor did I make any donation at the event.”

Andrei Borodin. Boris Johnson sat at his table at the summer party

Some glamour was provided by the presence of Peter Stringfellow, 73, the founder of the nightclub that bears his name, and his 31-year-old wife, Bella. A former Goldman Sachs banker and onetime Conservative donor, Richard Sharp, who sits on the Bank of England’s independent finance policy committee, was also present.

Press were banned from the event and helpers were “absolutely forbidden” from leaking details to the media, the internal documents show.

One former political regulator said that the details raise fresh questions about the UK party funding system. “These events are not transparent at all,” said Alistair Graham, the former chairman of the committee on standards in public life. “They are made to be private, cosy affairs where you pay for attention from a senior political figure, and if you are seeking to influence the government, you might have the opportunity to do so. We are vulnerable as a country to people getting private access to ministers for not too much money.”

A spokesman for the Conservative party said: “All donations to the Conservative party are properly and transparently declared to the Electoral Commission, published by them, and comply fully with Electoral Commission rules.”

The home secretary was placed with Lord de la Warr, director of Cluff Natural Resources, which is exploring underground coal gassification in Warwickshire, as well as Wafic Said, the Syrian-Saudi businessman who helped broker the al-Yamamah arms deal.

Wafic Said and wife

Among the lobbyists – some of whom have represented clients as diverse as the wife of the Syrian president Asma al-Assad, the Philip Morris tobacco company and Yukos oil – was James Henderson, chief executive of public affairs firm Bell Pottinger, which represents fracking company Cuadrilla among others. He hosted a table for friends, while his colleague Patsy Baker joined a table with justice secretary Chris Grayling.

“We do not go there to lobby ministers in any form,” Henderson said. “We go there to support the party. Apart from shaking a hand, I don’t believe I have ever spoken to a minister at any of these events.”

The summer party is the Conservatives’ second largest fundraiser after the winter “black and white ball”. Altogether, guests at the event have donated an estimated £22m to the Conservative party since records began in 2001, either in a private capacity and through companies of which they are directors.

On one table were representatives of the little-known Tory dining club, United and Cecil. Since 2001, its members have donated over £900,000 to the party through the club, without individuals being named.

The defence secretary, Philip Hammond, shared a table with the Saudi Arabian head of the Arab British Chamber of Commerce, Afnan Al-Shuaiby; the table was paid for by Lord Clanwilliam, a PR adviser who works for the government of Bahrain, which has faced criticism over its human rights record. Clanwilliam declined to comment.

The transport secretary, Patrick McLoughlin, was entertained by shipping to aviation magnate Constantine Logothetis, who has personally and through his company given £128,500 to the party. Also at the table was Laurent Cadji, another shipping company director. He did not respond to a request for comment.

Russian connection: Vasily Shestakov, Putin's judo partner

One of the most intriguing tables at the dinner features several prominent Russians connected to the Kremlin, including Vladimir Putin's wealthy judo partner.

Vasily Shestakov, an influential MP in Russia's Duma, sat a table hosted by the PR executive David Burnside. Shestakov is an old friend of Putin's and the co-author with Russia's president of several books on the sport, including Learn Judo With Vladimir Putin and Judo: History, Theory, Practice.

David Cameron speaking at the party to Vasily Shestakov (second right) and Russian billionaire Andrei Kliamko (right), translated by lobbyist Alex Nekrassov (centre)

But Shestakov is also a key player in the Kremlin's recent multi-pronged attempts to improve the country's battered international image. Shestakov has been given the job of boosting Russia's reputation in the UK. He is head of FIAS, the international federation for sambo, a Russian variation of judo.

At the dinner, Burnside introduced Shestakov to David Cameron. A photo on the sambo federation's website shows Cameron chatting to Putin's close friend, with Alex Nekrassov – who works for Burnside's PR consultancy firm New Century Media – translating. Also pictured is Andrei Kliamko, a FIAS executive with business interests in Crimea, who according to Forbes Russia is worth $1.9bn.

Burnside is a former Ulster Unionist MP, whose communications consultancy firm specialises in assisting wealthy Russians. "Cameron knows David from his political days," Tim Lewin, who sat with Shestakov, and advises New Century Media, said. "Cameron was looking for people to meet and greet. David grabbed him and introduced him to Shestakov."

Asked whether the meeting was appropriate, given the 2006 murder of Alexander Litvinenko in London by suspected Kremlin agents, Lewin said: "Shestakov is a senior MP." He added: "It's no different in my world, the finance world. If you want to impress people you have to introduce them to other big swingers. If you can have him [Shestakov] shake hands with the PM, it makes the wheels go round."

In May 2013 Shestakov – who speaks no English – was made an honorary freeman of the City of London. In June Shestakov hosted a sambo event at Kensington Palace, where he read out a message from Russia's president. Attendees included Prince Michael of Kent, Lord Simon Reading – also at Burnside's table – and a Russian business delegation. A friend of Silvio Berlusconi's paid for the evening and banquet.

Positive Russia charm offensive

The same month, June 2013, Lewin and Burnside founded the Positive Russia Foundation, an organisation designed to improve Russia's image in the UK. Lewin insists the foundation was his idea. According to Russian press reports, however, Shestakov was closely involved in setting up Positive Russia. Its purpose was to combat "anti-Russian propaganda" in the British media, Shestakov said.

The soft power project is the latest in a series of initiatives by the Russian government, which include the Kremlin propaganda channel Russia Today (RT). RT vehemently criticises the west, while ignoring the Russian state's authoritarianism. The St Petersburg news website Fontanka.ru – which interviewed Shestakov – described Positive Russia "as a new variant of RT, but under the patronage of English aristocrats."

According to Lewin, Burnside had also hoped to win a lucrative contract to promote sambo in the UK. In October 2013, "following conversations with Mr Shestakov", his company offered to arrange and promote a major sambo tournament in London. The 2014 event – named the President's Cup after Putin – would launch the sport on the world stage and "set a benchmark" for future UK-Russian relations.

New Century Media envisaged Putin handing the cup to the winning sambo team as well as a "prestigious black tie evening reception" afterwards. The PR firm promised "high-level dignitaries" from both countries would attend, including David Cameron, members of the royal family and Russian and British ministers. The venue would be Old Billingsgate Market.

The pitch explained: "Now one of Europe's most prestigious event venues, it hosts a variety of events throughout the year, including the Conservative Party's Summer Party, where Mr Shestakov was introduced to Prime Minister David Cameron this year by New Century Chairman David Burnside." The event would help rebuild Russian-UK ties, following "a slew of negative media coverage". The proposed budget, including Burnside's fee, was £1.5m. Lewin told the Guardian last week the contract "didn't go anywhere". But court papers show that New Century Media was earning huge sums during the same period from other wealthy Russian clients. It was also promoting Moscow, at the behest of Kremlin officials, as an international financial centre. One of the clients, Vladimir Makhlay, a businessman who fled to the UK in 2005, agreed to pay New Century Media £75,000 a month for strategic advice – "including support for Mr Makhlay's application for a British passport". Makhlay was allowed into Britain on an investor visa because he had "at least £1m" in British assets, the high court was told.

In return for £75,000 a month Burnside offered various services including "reputation management" and "personal introductions to an influential network of contacts". Makhlay, however, stopped paying after four months. New Century Media then sued in the high court, arguing successfully that the Russian had signed a year-long deal. According to election commission records, New Century Media donated £91,000 to the Conservative party in 2009 and 2010.

'This explains Cameron's spinelessness in relation to Putin'

The Guardian has learned that Burnside invited a senior diplomat from the Russian embassy in London to the same Tory fundraising dinner in 2012. The diplomat, Sergei Nalobin, is the son of a top-ranking officer in the FSB, the successor agency to the Soviet KGB. Nalobin's father was Litvinenko's boss in the 1990s.

"Nalobin wasn't supposed to be there. He was a last-minute addition. He spent the evening going round the tables, handing his business card to government ministers," one source said.

Nalobin played a key behind-the-scenes role in setting up the Conservative Friends of Russia, a pro-Kremlin parliamentary group. But the group collapsed in 2012, with key Conservative MPs resigning, following revelations of Nalobin's close links to Russia's powerful spy agencies.

Last week Lewin said the Positive Russia Foundation was still going – despite the sharp decline in Moscow-London relations following Russia's annexation of Crimea this spring. Although Cameron has condemned Russian aggression in Ukraine, Downing Street has so far not imposed visa bans on top Kremlin officials and oligarchs, many of whom have properties in London. Critics say the government is reluctant to act because it fears offending the City, for whom rich Russians are an important business.

Labour MP Chris Bryant, former chairman of the all-party parliamentary Russia group, said on Tuesday: "This shows the utter hypocrisy of David Cameron's Tory party and explains Cameron's spinelessness in relation to Putin. Voters will think that it's not just bizarre but despicable that Cameron will shake hands with, sit down to dinner with, and quite possibly take the money off, people such as these – the very people he is pretending to criticise over Crimea."

Burnside declined to comment. John Whittingdale MP, who sat with Shestakov on Burnside's table, said he believed that engaging with the Kremlin was the best strategy. Whittingdale, the chair of the British-Ukraine parliamentary group, said that he had a "robust exchange of views" last month with Russia's ambassador to the UK, Alexander Yakovenko. Lewin expressed similar sentiments. "I think isolating any authoritarian regime only makes it more authoritarian. If they [two opposing sides] don't speak to each other they end up throwing rocks over the fence."

Shestakov and Putin were members of St Petersburg's Yavara-Neva judo club. Many of the president's former sparring partners are now billionaires who occupy senior Kremlin positions. Shestakov declined to comment.