A government investigation into the Learning Link Multi-Academy Trust, which runs four primary schools in Dudley, revealed it spent more than £400,000 of taxpayers' money without following the correct procedures.
Learning Link, which is responsible for Sledmere, Kates Hill, Dudley Wood and Netherbrook primary schools, also doubled the pay of its then chief executive Paul Harrison without following due process.
The investigation, carried out by the Education and Skills Funding Agency, accused Mr Harrison of 'a lack of integrity', and said the Learning Link trustees had failed in their duty to hold the leadership to account.
It found that tens of thousands of pounds were spent with companies in which Mr Harrison had a direct personal interest.
The report also revealed that the trust had given Mr Harrison £38,500 to cover car leasing costs and private medical cover, without proper approval by the trust board.
Mr Harrison admitted that he did not use the money to lease a car, saying he considered it to be a pay rise.
The report found that the trust had misused public money and failed to manage conflicts of interest.
Former chief executive Paul Harrison's salary had been doubled without formal approval of the board.
Mr Harrison received more than £38,000 to cover car leasing and health insurance costs. No car was ever leased.
More than £100,000 was spent with five companies, four of which Mr Harrison had a direct interest. A fifth was run by the wife of one of the organisation's trustees. It said at least £15,600 of this money should have been referred to government officials for approval.
The investigation also identified a further £292,989 that was spent without any evidence of a formal tendering programme. There was also, in some cases, a conflict of interest, it added.
"These transactions breached the trust’s financial regulations and are deemed contentious and improper," said the report.
The ESFA report said Mr Harrison was originally appointed to work for two-and-a-half days a week, at a fixed daily rate. But his hours and pay were then increased to four, and then five days a week, without formal board approval.
It added: "Whilst receiving a salary for four days per week, the chief executive’s company received payment for an additional day of consultancy.
"This related party transaction was not formally approved by the trust board and breached the trust’s financial regulations."
Investigators added that in November 2018 Mr Harrison was given an enhanced contract, which included the provision of a leased car costing the trust up to £11,400 a year, plus a £5,000 lease deposit and £3,000 healthcare package.
Mr Harrison was given £38,250 to cover these costs, but later told investigators that no car had been leased.
"The contract was not formally approved by the trust board, although the chair signed the contract on behalf of the trust," said the report.
"The car leasing allowance was paid to the chief executive, despite no evidence that a car had been leased. The ESFA deems the £38,250 paid for the car leasing allowance as irregular and a misuse of public funds."
Then chairman of trustees Grenville Earney said he "anticipated a car had been leased", but took no action to check this was the case.
The report said the trust had been unable to demonstrate that decisions which benefited Mr Harrison had been made independently of him, or that conflicts of interest had been managed.
It also revealed that Mr Harrison had emailed solicitors with a draft of his enhanced contract in November 2018, along with a letter purporting to be from Mr Earney offering him the job.
The letter was dated February 17, 2017. However, Mr Earney did not become chairman of trustees until September 2018, and told the ESFA he was not aware of the letter.
The report concluded that Mr Harrison had been unable to assure the ESFA and Parliament of a high standard of probity in the management of trust funds.
"In addition, the findings demonstrate a lack of selflessness and integrity in managing the process for his contracts and remuneration, including not managing inherent conflicts of interest," it added.
The trust, which was set up in 2017, was told it would be stripped of its responsibilities last year following a warning by the schools commissioner for the West Midlands Andrew Warren.
It now has a new board of trustees and leadership team, and is in the process of transferring the schools to new trusts.