At Cardiff crown court yesterday Landare Investments blamed a conspiracy of leading councillors and officials for the failure of the project seven years ago.
Among those accused were the WDA and Rhondda Cynon Taff CBC. The company is suing 12 individuals including former WDA chief executive Phillip Head and former chief executive of the abolished Cynon Valley BC Tony Roberts.
All the named individuals and organisations strongly deny the accusations.
Landare's case is that the public bodies and their officers acted beyond their legal powers - misfeance in public office.
The first witness is expected to be called tomorrow.