Green Councillor Ian Middleton - a member of the council's Overview and Scrutiny Committee - asked the council for evidence it had used to make assumptions about future income from the shopping centre. He has been denied details supporting the council's claims that the centre will break-even in the next financial year on the basis of 'commercial confidentiality'.
The council says specialists have advised it on financial forecasting and they cannot share sensitive information.
Mr Middleton wanted the information to enable him to scrutinise the validity of the council budget properly.
He said that, as other members of the council have presumably seen the figures, he should also be able to view them especially as a member of the scrutiny committee.
He said he would abide by any commercial confidentiality and, as a retail analyst himself, he would be able to assess if in his opinion the forecasts made in the council's budget were realistic.
He said: "I recently requested the report that informed the budgetary assumptions underlying one of the most significant investments by this council – Castle Quay. But I was told I didn't need to know those details. I contest that. Current forecasts are that gains over the next year will almost exactly match losses in the previous year. To me that sounds like convenient guesswork.
"If that prediction proves correct then it's good news. For the first time in years there's a hope that this dubious investment, that has so far lost more than two thirds of its market value, will actually break even. Most people wouldn't see that as a reason to celebrate four years into an investment cycle, but considering that so far, this adventure has been nothing but a burden to taxpayers, it's an improvement.
"But without sight of the information supporting these predictions it's impossible to know if they are realistic. If they're not, this could have serious implications for the council's financial position over the coming financial year and as a member of the council, representing thousands of residents in Kidlington, I am entitled to be forewarned of that possibility."
Mr Middleton said: "I have made it clear to officers that if they continue to deny me the information I require I will have no choice but to make an official complaint to external regulatory bodies. I am still awaiting their response."
In a statement Cherwell District Council said: “The Council is committed to transparency and good governance over the delivery of all its projects. As part of the normal checks and balances of local democracy members have the opportunity to scrutinise Castle Quay through various committees such as Overview and Scrutiny.
"We draw on the advice of specialist retail advisers and specialist accountants to advise us on the financial forecasting of this important and exciting regeneration project and this position is monitored and reported as part of the Council’s overall monthly budget monitoring procedures.
"As with any similar venture, it is important that commercially sensitive information is not always shared, as to do so would harm the businesses involved at a time when the retail sector has suffered considerably in the aftermath of the COVID pandemic.
"The Council is working hard to regenerate Castle Quay, and to make it a vibrant place which the local community can enjoy. The Council will be providing a briefing to all its members on the project in the coming weeks.”
The council said the regeneration of the Castle Quay area was designed to 'future-proof' the local economy.
Mr Middleton was not content with the response. He said: "I have not been provided with any of the background information I have requested, as a member of the Overview and Scrutiny Committee or as a reserve member of the Accounts, Audit and Risk Committee.
"As such I would have thought that I'd be trustworthy enough to see the underlying assumptions being made on such an important element of the council's financial forecasting. I am perfectly aware of my responsibilities as a councillor with regard to commercial confidentiality, as well as through my own professional experience.
"My understanding is that other members of the council have had sight of this information so I am at a loss to understand why I am being denied access. If I were a suspicious man, I may conclude that the council has something to hide."
Last September Mr Middleton said Castle Quay had lost £47m of its value and council tax payers were losing services to fund interest charges. See story here.
Mr Middleton said he was at a loss to understand other aspects of the council's retail and leisure strategy. "For example bowling facilities are being de-funded in Bicester due to lack of demand, yet in Banbury, where there's already an existing bowling offer, we're being told there’s a market for even more," he said. "If the same sort of assumptions underly the budgetary predictions surrounding Castle Quay, I'm not confident in the council's huge financial commitment so either the existing shopping centre or the new waterside development are prudent."