Three consultancy firms were paid a combined £600,000 over four years for reports that have never been made public, documents obtained by Brit7 News show.
The reports covered town-centre regeneration, car parking and a proposed leisure scheme that was later abandoned.
Two councillors told us they had asked to see the reports and been refused.
The council says some of the work contained commercially sensitive information and that it “always seeks value for money”.
You can read the full list of payments, and the questions the council has not answered, below.