You've heard of Michael Ashcroft – the billionaire who supposedly "owns" the Tory party – but what of Irvine Laidlaw or Michael Spencer?

Although he was targeted by the press because of his questionable tax status, Ashcroft has for many become synonymous with big cash donations and the influence that comes with it. But he is by no means the Conservative Party's biggest donor. New research by the LSE reveals the way in which huge donors are able largely to avoid publicity, while staying completely within the law, by splitting up donations between family members or personal and company donations.

By collating cash given by the Tories' biggest donors, as well as that given by their husbands, wives, family members, business partners or companies, researchers have built up a detailed picture of the people funding the party.

They found that, in the past decade, £72m – more than half of the party's declared cash donation income – was donated to the Conservative Party by just 50 of these "donor groups".

Of this, £44.5m – amounting to just under one-third (31.9 per cent) of total donations – came from the top 15.

The Tory donor Stuart Wheeler made headlines last month when he said that it was "absolutely natural and unobjectionable" for big donors to gain influence over policy, and called for the cap to be scrapped. In response to the charge that this "big donor" culture had made politics less fair, he said: "Fairness isn't the be all and end all."

Evidently, some tightening up needs to be done to ensure that the spirit as well as the letter of the law placing a cap on donations is obeyed.

You can view the list of big cash donors to the Conservative Party here.

NOTE: There is no suggestion that the Conservatives are unique in this respect. Previous LSE research highlighted the importance of big donors to all three of the major political parties.