Forest of Dean District Council launched an investigation after receiving a complaint alleging that two dwellings had been constructed in addition to nine that had been approved on appeal at the site in Culver Street in the town of Newent.
The appeal decision in 2013 granted the original consent for nine homes and the developer, who the council has not named, was granted permission for amendments to the permission last year.
But the council’s investigation found that there were "several discrepancies when compared with the approved plans" attached to the permission.
Changes outlined in the planning officer’s report to last week’s planning committee meeting included changes to windows, alteration to the road layout and parking arrangements, and the reduction in one of the homes’ rear garden depth.
It was also found that the site had been "significantly enlarged, with a garage block located to the north of the site not constructed and instead additional dwellings being erected up to damp course level".
"It is clear that the development undertaken is fundamentally different when compared with the approved scheme," the report said.
"As a consequence, it is considered that all of the works undertaken on site are unauthorised", it said.
The council’s enforcement notice orders the developer to "demolish all of the building works and dig out all foundations, including any associated drainage".
It says the notice must be complied with within a deadline of nine months.
"The bottom line is that there is nothing on this site that has been built in accordance with the plans and therefore there is no planning permission, and so the council has no control over how that site is finished off," the council’s development manager said at the committee meeting.
"That is not an acceptable place for the planning authority to be in."
Planning contacted the developer for a comment but had not received a response at the of writing.
The planning officer presenting the case at the committee said the developer had started demolishing the unauthorised works.
According to the officer, the developer claimed the site builder had started the works prematurely and has now been dismissed from the project.
"The developer is open to discussions seeking a way forward to avoid any costly appeals," he added.
Yesterday, government watchdog the Local Government Ombudsman criticised a national park authority for charging residents for planning enforcement work, saying the policy was introduced on "limited and uncertain grounds".