Lord Heywood, the former head of the civil service, will be singled out for repeated criticism in the review ordered by Boris Johnson into the Greensill saga, The Telegraph understands.
The probe into how the Australian financier Lex Greensill gained such access in Government during David Cameron' premiership, and the subsequent lobbying from Mr Cameron once out of office, could be published as early as Thursday.
Mr Johnson ordered the inquiry, which was led by the lawyer Nigel Boardman, in April after a slew of headlines about how Mr Greensill won government contracts for his supply chain finance plans.
The Boardman review is also expected to call for tighter rules on how businessmen are granted government access and lobbying by former ministers.
Mr Cameron was working for Greensill Capital, a finance company run by Mr Greensill, when he repeatedly sought government support for the firm after the Covid pandemic struck.
The Boardman review has been submitted to the Government and copies have been scrutinised by officials.
Lord Heywood, who was Cabinet Secretary from 2012 to 2018, befriended Mr Greensill when they worked together in the private sector and championed his work inside government. Lord Heywood died in 2018 after being diagnosed with cancer.
A well-placed source who has seen a copy of the Boardman review told The Telegraph the findings were "not very complimentary" about Lord Heywood, who comes in for "criticism".
"The evidence the review has gathered points quite largely to him being responsible for the insertion of Greensill into government," the source said.
Mr Greensill was reportedly able to access multiple government departments as he pushed his supply chain finance proposals. He also had a government business card showing an official email account. Defenders of his proposals argue they were well-intentioned attempts to improve cash flow issues inside the Government.
At the time, figures in Mr Cameron's administration were championing the use of private sector approaches to improve civil service efficiency.
The former Prime Minister is also understood to not come away from the review unscathed, with the source describing him as not "escaping" criticism for his lobbying efforts.
Mr Cameron has defended his role working for Greensill Capital, arguing he believed in the benefit supply chain finance could bring. However, he has expressed regret at the informal way he sought Greensill's inclusion in a government financial support scheme, texting and emailing ministers and officials after the pandemic hit.
Lady Heywood, Lord Heywood's widow, raised concerns about the Boardman review after being told by The Telegraph about the expected criticism contained in the report.
She told The Telegraph: "Nigel Boardman has run a deeply flawed process from beginning to end, with the sole aim of making Jeremy the fall guy for events that occurred long after his death. Heaping the blame onto the only person unable to defend himself clearly provides a convenient diversion from the current Government's handling the Greensill Capital collapse.
"All my attempts to have Jeremy's voice heard have been systemically blocked or ignored. The result is the cynical gagging of a dead man who devoted his life to public service."
Mr Boardman has been a partner at Slaughter and May since 1982. He is also the deputy chairman of the British Museum and vice-president of Save the Children UK.
Government officials defended his suitability to oversee the review when his involvement was announced in April, arguing that he would be independent and fair.