根據 "地方民主報告服務 "看到的 "保證林肯郡 "的報告，該委員會 "並不總是符合地方政府所期望的良好治理原則，也沒有清楚地表明資金的價值"。
Four trees were set to be chopped down by Newark and Sherwood District Council to make way for the extension in London Road, Newark.
According to the report by Assurance Lincolnshire, seen by the Local Democracy Reporting Service, the council "did not always conform to good governance principles expected in local government nor clearly demonstrate value for money".
It adds: "Whilst we acknowledge the commercial sensitivity of the matters under consideration - key stakeholders had very little opportunity to effectively engage with the council in the early stages of the process.
"The situation the council found itself in at the end of the transaction for the London Road car park extension meant that it was in a position of moving forward with a 'least worst' option - which was not necessarily the best value option in financial terms."
The agreement committed the council to building the car park and to pay the company £30,000 per year in rent for 25 years, following an initial two-year, rent-free period.
The council reversed the decision in November last year, agreeing to buy back the land for £450,000 and not build the car park extension, ensuring the trees escaped being felled - though one has since been chopped down after being found to be diseased.
A statement from Protect Newark's Green Spaces said: "We expect that NSDC officers and members... will publicly and sincerely apologise to council taxpayers across the district for their failures of governance and due diligence which have wasted so much of their money."
The report found the sale of the municipal building and adjoining land, the lease back of the land and the subsequent buy back of the land has cost the council more than £500,000.
John Robinson, chief executive of Newark and Sherwood District Council, said: "Quite rightly, questions were asked about how the council found itself in this situation and this has been the focus of the independent review.
"The review highlights things that we got wrong and things we should have done better. We need to hold our hands up to these things and learn from them."