In one case the panel looked at how private property developers have ended up owning 90% of the site.

The report says they put no money into the scheme, but they have made money on the back of public sector investment of more than £560m.

The deal, it is said, should have been scrutinised more by the Tees Valley Combined Authority – all five of the Tees Valley local councils.

More broadly, the review found a culture of excessive confidentiality and a lack of transparency at the development corporation.

The final conclusion states that “inappropriate decisions and a lack of transparency which fail to guard against allegations of wrongdoing are occurring, and the principles of spending public money are not being observed”.

The review panel makes 28 recommendations, many of which propose more openness and more oversight by the Tees Valley Combined Authority.