The proximity of senior cabinet members to powerful business leaders and lobbyists has alarmed transparency campaigners leading to renewed calls for reform around the issues of disclosure.

‘There’s a real problem with big money in British politics,’ said Alexandra Runswick, Unlock Democracy director. ‘Whether it is party donors given seats in the House of Lords or people buying dinner with David Cameron, the public feels our politics is for sale – that politicians listen to donors and lobbyists but not voters.’

Tamasin Cave, director of lobbying campaign group, Spinwatch, said: ‘Buying a seat at a minister’s table provides these bankers, foreign businessmen and lobbyists with an opportunity to discuss their concerns, whether its taxes, regulation or policy. It’s a straight up case of cash-for-access.’

Labour has also been holding a series of business dinners. Last month a dinner hosted by shadow work and pension minister, Chris Bryant in the Grand Connaught Rooms in Covent Garden, London, saw lobbyists and executives from security companies, private healthcare firms and the property industry mix with Harriet Harman, Labour’s deputy leader, Chuka Umunna, shadow business secretary, and Emma Reynolds, shadow housing minister.

Labour’s big ticket fundraising dinner and auction this year takes place on July 9 at The Roundhouse in Camden, London. The £15,000 premier tables only includes a £7,000 donation meaning that under current rules, tickets to the event need not be disclosed.

Earlier this week, Len McCluskey, leader of Unite, confirmed the UK’s biggest union will heavily back Labour with cash in the forthcoming election campaign.

The Conservative summer party, titled, ‘40 [seats] to gain 40 to hold’, placed MPs in constituencies with slim majorities or prospective candidates on many tables.

Shore Capital

The event was sponsored by Shore Capital, an AIM-listed West End-based boutique investment bank run by Howard Shore. Shore and his company have donated £499,330 to the Conservatives since 2006.

Shore and his wife, the chair of the organising committee for the event, hosted David and Samantha Cameron on their table. The investment bank also sponsored two other tables where energy minister Michael Fallon and home secretary Theresa May were seated. May shared a table with Lord De La Warr, non-executive director of Cluff Natural Resources which is exploring underground coal gasification in Warwickshire.

Asked why Shore Capital sponsored the party, the company said in a statement: ‘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.’

Russian connection

Among the more surprising guests were a number of business men linked to Russia. These included Alexander Temerko and Andrei Borodin, who were sitting with London Mayor, Boris Johnson.

Also present was Vladamir 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.

There were also 19 lobbyists and public relations specialists at the party representing Gulf states, fracking firms, oligarchs and banking giants.

Among these high profile PR specialists was Lord Clanwilliam whose firm represents the government of Bahrain. He headed one of the more prominent tables, hosting defence secretary Philip Hammond. Clanwilliam declined to comment on his attendance.

Also attending was James Henderson, chief executive of public affairs firm Bell Pottinger which represents fracking company Cuadrilla. 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.’

Henderson added that his colleague Patsy Baker was at the party ‘in a private capacity as the personal guest of her host. She didn’t raise any issues on behalf of Bell Pottinger or her clients.’

The finance sector formed the largest contingent at the event. In total, there were 73 hedge fund tycoons, private equity financiers and wealth managers. Among them were some of Mayfair and Belgravia’s most powerful hedge fund names led by heavyweight party donors Sir Michael Hintze of CQS and Andrew Law of Caxton — both former executives at Goldman Sachs.

Premier tables at last year’s party cost £1,000 per guest. Standard tables were charged at £400 per guest.

There is no precise way of knowing how much was raised from last year’s event. Political donations are only disclosed above a £7,500 threshold. But at fundraisers the value of the meal or prize is deducted. This means many donations may fall below the threshold and so will not be disclosed.

But in the week following the event, Electoral Commission data shows the Conservatives received £1.1m. This is over three times the Conservatives’ average weekly donor income.

Guests at the party and the companies they represent have donated a disclosed £21.9m to the Conservatives since Electoral Commission records began in 2001. This is 10 per cent of the £219.7m of disclosed donations to the party in the same period. (All donations above £500 have to be declared, and any above £7,500 are disclosed on a register kept by the Electoral Commission.)

Since the June 24 event, guests have donated a disclosed £5m to the Conservatives.

On one table was a representatives of the little-known Tory dining club, United and Cecil. Since 2008, its members have donated £909,095 to the party through the club. Almost all these donations are made anonymously.

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.’

Spinwatch’s Tamasin Cave, said: ‘Our government has promised to be ‘the most transparent in the world’, yet David Cameron won’t even publish the names of his guests at these events, which is just one of countless donor dinners.’