Lex Greensill enjoyed an “extraordinarily privileged” relationship with government and David Cameron “could have been clearer” about his relationship with the financier’s firm, a review has found.

The long-awaited report commissioned by Boris Johnson in response to concerns over the former prime minister’s lobbying for the collapsed firm was published on Thursday.

Mr Cameron and late cabinet secretary Lord Heywood received some criticism in lawyer Nigel Boardman’s report, which Labour described as a “classic Boris Johnson cover-up and whitewash to protect the Government”.

It was launched in April after it emerged Mr Cameron privately lobbied ministers to attempt to try to secure access to an emergency coronavirus loan scheme for Greensill, where he took up a role in 2018.

Mr Boardman found that the Australian businessman’s earlier role in government during Mr Cameron’s premiership enabled him to promote a financial product that had little or no “material benefits to government”.

But Mr Boardman concludes that the former Conservative Party leader “did not breach the current lobbying rules and his actions were not unlawful”, neither does the evidence appear to show he had a role in bringing Mr Greensill into government.

However, the 141-page report says that Mr Cameron “on occasion understated the nature of his relationship with Greensill Capital” when lobbying the Treasury over a coronavirus scheme.

It adds that “Mr Cameron could have been clearer about his relationship with Greensill Capital” in his communications with the ministers and officials in the Treasury and the Bank of England.

Mr Cameron told Mr Boardman that Greensill Capital was paying him “a good amount of money every year” and he had equity and participated in a discretionary uncapped bonus scheme.

The review also notes that Mr Cameron “accepted that he used methods of communication that were, in hindsight, not the right way for a former prime minister to engage with government”.

Elsewhere, Mr Boardman discusses Mr Greensill’s access to power and his ability to promote his supply chain finance product.

“It is clear from the evidence that I have reviewed that Mr Greensill had a privileged – and sometimes extraordinarily privileged – relationship with government,” it says.

The review finds Lord Heywood, who died in 2018 and had previously worked with the financier at Morgan Stanley, was “primarily responsible” for Mr Greensill securing a role in government.

There was mention of Mr Greensill’s appointment to the Cabinet Office’s economic and domestic secretariat being referred to an “approvals board”, to which Lord Heywood, responded: “Sure – though it is bureaucracy gone mad!”

Mr Greensill was given two sets of official IT and security access for the Cabinet Office and, with Lord Heywood’s support, No 10, the review says.

The role in government provided Mr Greensill “with a marketing platform for Greensill Capital’s business with the private sector”.

“This enabled Mr Greensill to promote a product which did not, in fact, provide material benefits to government (except possibly in relation to the pharmacy supply chain finance programme, although even here the benefits are disputed), although it could have been of benefit to his incipient business and was of immediate benefit to his former employer, Citibank,” the report says.

Mr Boardman said, from the evidence he has seen, Mr Cameron “had no responsibility” for bringing Mr Greensill into government and that his promotion of supply chain finance “was understandable in light of the briefing he received”.

In a statement, Mr Cameron welcomed the review by Mr Boardman, who is a non-executive board member of the Department for Business, Energy and Industrial Strategy.

“I am pleased that the report provides further confirmation that I broke no rules,” he said in a statement.

“It also makes plain that I was not responsible for bringing Lex Greensill into Government or any of the arrangements connected to this.

“I was open about my relationship with Greensill Capital, and acknowledge the importance of being explicit in this regard.”

But Labour’s deputy leader Angela Rayner said: “The Greensill scandal proves beyond all doubt that the rules that are supposed to regulate lobbying are completely unfit for purpose and require radical and immediate overhaul.”

She said it “was set up as a classic Boris Johnson cover-up and whitewash to protect the Government – a government non-executive director whose firm worked with the Treasury on corporate financing and had previously campaigned against lobbying reforms was appointed to lead a review”.

In April, Mr Cameron accepted that he should have communicated with the Government “through only the most formal of channels” rather than text messages to Chancellor Rishi Sunak as he acknowledged mis-steps over the controversy.

Mr Boardman concluded that lobbying “is vital to the proper functioning of democracy” and “while there are improvements to be made, the current system and those operating within it worked well”.