A campaign is growing to save a complex of Grade I listed buildings in Norfolk from being turned into a housing development. The derelict 13th century Abbey Barns in Thetford are believed to be the only example of agricultural buildings within the site of a Cluniac Priory in Europe.

A campaign is growing to save a complex of Grade I listed buildings in Norfolk from being turned into a housing development.

The derelict 13th century Abbey Barns in Thetford are believed to be the only example of agricultural buildings within the site of a Cluniac Priory in Europe.

But a developer now wants to build 26 new residential units on the historic site at Monksgate and convert the existing listed cottages and barn into five homes.

The plans by owners HG Developments, of Tacolneston, near Norwich, are set to come before a Breckland Council planning committee later this summer.

However, there is already a groundswell of opinion against the density of the proposed new development and the scheme to permanently remove the historic buildings from public use, with a petition signed by more than 200 residents.

Stuart Wilson, from the Thetford Society's environmental committee, said the 0.9ha site, which was part of a Scheduled Ancient Monument, was “crying out” to be converted into a visitor centre for the nearby Cluniac Priory ruins, which would help boost Thetford's tourist trail.

The society has written to the chief executive of English Heritage, which looks after Thetford Priory, asking the agency to intervene.

“The Abbey cottages and barn are two of only eight Grade I listed buildings in Thetford. To remove a quarter of the Grade I listed buildings from public access would be a travesty which, in the future, could not easily be reversed.”

“If these important buildings are turned into residential their potential as a heritage focal point in the future will be lost,” said Mr Wilson.

The buildings, which were originally an aisled hall and granary to the Thetford Priory, closed as a highways depot in the late 1990s and were sold by Breckland Council to the highest bidder in 2002. The flint-clad barn and two cottages are currently on English Heritage's Buildings at Risk register.