When permission was granted for a nine-metre high sound barrier between a new housing development in Stevenage and the A1(M), the council's decision-maker was crucially unaware that a noise consultant appointed by the council had advised that the "developers need to remodel their site" over the proposed barrier.

On land west of the A1(M) and south of Stevenage Road in Todds Green, 133 homes are being built. When a sound barrier began being erected in April, people called it an "eyesore" and "like a prison wall", but the developer said it was the "most suitable option for noise mitigation".

The Comet has now learned that a noise consultant, appointed by Stevenage Borough Council's environmental health team to provide them with professional advice on the detailed noise mitigation measures, had raised concerns about the barrier plans.

In a letter to a concerned resident, seen by the Comet, the council's assistant director of planning and regulation says the consultant had advised that the developers needed to "remodel the site in relation to the proposed mitigation," to "include reflective factors" and "modern understanding of ground effects when screening," as well as "determine western boundary treatment to address any excess commercial noise resulting".

It says the environmental health officer "tried to capture these comments" and pass them on to the planning case officer, but failed to "explicitly reference the need for an additional assessment or modelling in regards to reflective noise/ground effects of the screening."

Instead, environmental health advised planning not to discharge the planning conditions due to height concerns.

In his letter, the council's assistant director of planning and regulation says: "I have spoken to the case officer and, had he been aware of the need for additional modelling, especially on reflective noise, he would have sought this additional modelling from the developer.

"His interpretations of the [environmental health officer's] comments were that, if there was no objection to the height of the fence from a planning perspective, there was not a requirement to seek an amended design."

Consequently, the case officer discharged the planning conditions, allowing the barrier to be erected.

The council has been asked to comment.