Yarm School's plans to sell its existing sites for £25m and relocate to the edge of town may have to go before a lengthy public inquiry.

The independent school's headmaster, David Dunn, revealed the plans to the D&S Times two weeks ago.

He said the 25-year-old school hoped to leave the historic Friarage and prep school sites in Yarm town centre for Green Lane. The preferred bidders for the old sites were Wimpey and Bellway Homes.

The proposed new site is much closer to Yarm railway station and the A19, but also to Conyers School.

Yarm Town Council last week expressed doubts over claims the relocation would ease the area's notorious traffic congestion.

The whole planning process could take years because the school hopes to build on green wedge land, which goes against Stockton Council's planning guidelines.

This week, Coun Jennie Beaumont, a Kirklevington ward councillor on Stockton planning committee, said she believed the plan would be called in for inspection by the Environment Secretary.

"This proposal is a departure from the local plan. You have to ask whether there is any intention to allocate that land for any other purpose.

"My understanding is that it is not allocated. The local plan is just going through its first stages and has a long way to go. At the moment, this proposal would probably be called in by the Government. I'd expect there to be a public inquiry," she said.

The debate over greenfield development has intensified recently, with the Stockton branch of the Council for the Protection of Rural England claiming too much green space is being lost around Yarm, Ingleby Barwick and Egglescliffe.

However, Stockton Council this week suggested a school could be built at Green Lane under certain strict conditions.

A spokesman said: "There are no plans to develop the Green Lane area at present."

However, he added: "Schools can be acceptable in that sort of location, provided stringent conditions are met concerning the size of the development, landscaping and building coverage. The idea of a school is neither automatically supported nor dismissed."

Supporters hope school traffic and congestion in Yarm could be reduced if the relocation went ahead, given the proposed site's proximity to Yarm railway station serving Northallerton, Thirsk, Eaglescliffe and Thornaby.

Facilities at Thornaby are being improved and Yarm station has been been slightly enhanced with a bigger car park and bus stop.

The council was asked whether increased passenger-numbers at Yarm could lead to better facilities and more trains. However, a transport spokes-man was unavailable for comment