Commercial confidentiality "taken to extremes" kept councillors in the dark about a pact binding a local authority to Tesco, a report has revealed.
Tesco had proposed building on the site of council-owned flats
North Norfolk District Council signed the deal with the store in May 2003.
The deal, signed by senior officers, to build a Tesco store on council land in Cromer Road, Sheringham, Norfolk, was made public in 2006.
The report, published on Wednesday, suggests the deal was "officer led" at a time of "weak political leadership".
The report says the council's executive committee knew about the negotiations with Tesco but not the details.
The deal was signed by the council's then chief executive Bruce Barrell and Graham Bull, the then director of health services.
North Norfolk District Council has investigated the pact
The report finds that there was "no evidence of impropriety in the deal with Tesco but that confidentiality was taken to an extreme which meant members were not able to take decisions based on all the facts".
The report, commissioned by the council after it found out about the deal, says: "Interviews with officers characterised the process leading to the agreement in 2003 as being 'officer led'.
"It was identified that there was weak political leadership, i.e. the council had no overall control ... officers would provide leadership."
The agreement was signed between one administration leaving office after the 1 May elections in 2003 and the newly-elected members taking up their posts in the new executive committee.
A number of councillors and local residents who had opposed plans for a Tesco supermarket on council-owned land in Sheringham only heard about the deal three years later.
Earlier a Tesco spokesperson said: "It (the deal) precludes the council from promoting an alternative council-owned site for supermarket development but does not prevent the council granting planning permission to other retail developments on non-council land.
"It is therefore wrong to suggest that the agreement means that no other rival supermarket could develop a store in Sheringham."