Campaigners opposed to a major new housing estate in Horncastle are calling on the district council to back their on-going fight.
East Lindsey District Council rejected an application by Gladman in December for up to 350 new homes at Langton Hill.
But Gladman have submitted an appeal and the process could result in a lengthy - and expensive - public enquiry.
A national body, the Planning Inspectorate, will decide whether to hold an enquiry, or a hearing, after considering all the relevant information.
Confirmation of the appeal marks a worrying situation for members of the Save Langton Hill campaign group.
Their spokesman David Rice said: “We had been expecting this and we’re ready. ELDC have always said they would fight an appeal and we hope they keep to their word.”
Mr Rice said it was difficult to comment on the process because details of the appeal were still emerging.
He added: “We don’t know what the grounds are but it is worrying.
“Our position hasn’t changed. We believe Langton Hill is completely the wrong place. It is a hill top development which is one of the main reasons ELDC rejected the application.
“The location hasn’t changed. If it was a level site, we would be in trouble.
“If this gets through on appeal, ELDC might as well rip up all their planning policies and let people build anywhere.”
Residents have until April 21 to submit their views about the proposed development although initial objections are still valid.
Mr Rice added: “All the concerns are still there - increased traffic, flooding risk, school places and the fact no-one supported this.”
Mr Rice said the campaign group understood Gladman were hoping for a six-day enquiry in June and the company maintained strict planning conditions could overcome concerns about their proposal.
A spokesman for ELDC said: “An appeal has been submitted to the Planning Inspectorate who has confirmed that this is a valid appeal.
“We have notified all those who expressed an interest in the initial application.
“The nature of the appeal - whether it will take the form of a public inquiry or hearing - has not yet been determined.
“The outcome will be determined by the Planning Inspectorate. “.