David & Samantha Cameron arrive at the 2014 party/Getty images

A doorstep lender, property moguls and controversial bankers were among guests worth £22bn at the Conservatives’ most important fund raising event this year.

The list of 570 guests at the Tories’ Black and White party in February will heighten concern that wealthy individuals are potentially gaining access to ministers in secret.

A leaked table plan analysed by the Bureau shows that the prime minster and 21 other ministers including George Osborne were due to attend the event. Most of these have not confirmed their attendance at the fundraiser.

Earlier this year the Bureau of Investigative Journalism revealed how lobbyists and oligarchs had flocked to the 2013 Tory summer party attended by David Cameron and senior members of his cabinet.

Just like at that event, some guests at the black and white party sat with ministers whose portfolios were relevant to the guests’ financial interests.

The Bureau of Investigative Journalism can reveal that, at the February 5 event:

*Work and pensions secretary Iain Duncan Smith, who has overseen a wide-ranging programme of welfare cuts, dined with directors of a doorstep lending company;

*The then housing minister Kris Hopkins sat with prime central London’s largest residential landlord and two men whose companies operate in the “trophy” homes sector;

*Michael Fallon, who was energy minister at the time, joined a table hosted by the directors of a firm that builds components for oil and gas platforms and offshore wind farms.

Related story: Access all ministers: billionaires and lobbyists at lavish party with David Cameron

Seats with senior Tories came at a cost: “premier” tickets were charged at £1,000 compared with £450 for an ordinary ticket.

Under ministerial disclosure rules, meetings with business executives or individuals on a one-to-one basis or in ministers’ offices have to be declared. When ministers attend a reception or other large group event in their official capacity this must also be disclosed, but there is no requirement to list individuals met on these occasions.

All party political functions such as conferences and fundraisers are exempt from these rules.

Until the Bureau’s previous story, details of guests attending and the seating arrangements at the Tories’ fundraisers were unknown to the wider public.

Sir Alastair Graham, former chairman of the Committee for Standards in Public Life, said the public had a right to know that events were taking place and who was attending “so that we can track, over the forthcoming months if policy sweeteners have been promised as an incentive to attract donations.