Putin allies and pro-Russian lobbyists attended a Tory summer party while Russia was in the process of passing its notorious anti-gay law, it has been revealed.

According to the Guardian, a number of Russian politicians attended the party on June 24 last year, two weeks after the Russian parliament unanimously voted in favour of the law and one week before Putin signed it into law.

David Cameron, Theresa May and Boris Johnson were among the leading Conservative politicians in attendance.

Russian MP Vasily Shestakov, who voted for the anti-gay law, was in attendance at the event, according to a leaked seating plan.

Shestakov – who has been tasked with improving Russia’s reputation in the UK – shook hands with David Cameron at the event.

A member of the party told the newspaper that the handshake was to “make the wheels go round”.

Also at the £400-a-seat table was Alexander Kuznetsov, the president of the Multisport Assocation of Russia, and Timothy Lewin, the founder of the pro-Kremlin Positive Russia Campaign.

The table was sponsored by David Burnside, a former Ulster Unionist MP who is now a public relations expert with Russian clients.

Others at the table were Tory MP John Whittingdale, Russian billionaire Andrei Kliamko, BP’s vice-president for Russia Peter Chow, Lord Simon Reading and two more representatives of Lewin and Burnside’s PR firm New Century Media..

Press were barred from the event and staff were forbidden from leaking its details, according to internal documents which the Bureau of Investigative Journalism say they have seen.

The 450 attendees had a combined wealth of over £11bn.

This year’s party will take place tonight at the Hurlingham club in London. The guest-list for tonight’s event is not known.

John Whittingdale and New Century Media had not responded to a request for comment at the time of publication.