Concerns have been raised over whether data supplied on school and roads capacity will allow an informed decision to be made on plans for 255 new houses on the outskirts of Dereham.

Dereham Town Council's plans committee discussed Hopkins Homes' renewed application to build a housing estate on Yaxham Road in Dumpling Green, which was submitted to Breckland Council earlier this year.

Town clerk Tony Needham said he had uncovered a 'number of issues', mainly relating to responses from Norfolk County Council's education and highways departments, and questioned whether the information available is sufficient for Breckland's planning committee to determine the application.

He said both Toftwood schools are operating at capacity, and the development would bring an estimated 33 pupils to Toftwood Junior – adding three or four children per class, thus pushing class sizes over their legal maximum.

He felt that the county council's assessment did not take account of whether it is feasible to expand the schools with the 'Section 106' funding provided through the development.

Mr Needham also said the assessment of the likely impact on the road network was based on a 2009 traffic survey and 2001 car usage data, with junctions at Tavern Lane and the Yaxham Road roundabout already approaching saturation point.

He suggested the county council should refresh its assessments using updated surveys and said none of the supplied information had taken account of the cumulative effect of other development in the town, either from other recent applications or from sites allocated within the district's Local Development Framework (LDF).

The town councillors resolved to write to the county's education and highways departments raising 'serious concerns' about the data on which the decision will be made. The letters will be copied to Breckland planners, and to Mid Norfolk MP George Freeman.

Mr Needham said: 'The more I looked into it, the more I started to get concerned. I was under the impression that the county council looks into all these things, but they look at each development in isolation, not planned development as a whole, to see what the impact would be.

'For Dumpling Green they have looked at these figures from 2010 but they didn't take into account the cumulative impact of all the planning applications since then, and all those proposed under the LDF, or all those villages who feed into Dereham.'

Town councillor Phillip Duigan, who is also a Breckland district councillor, said: 'The people on the planning committee have to make very difficult decisions. The county council does not seem to have taken into account any of these cumulative developments, including the sites included in the local plan. Until we can do that, all our arguments are irrelevant.'

Deputy mayor Tim Birt added: 'In other words, they (the planning committee) are going to be forced to make the wrong decision, because they are making it on the basis of information that is out of date.'

Town councillor Robin Goreham said: 'A lot of the people who have lived in the town for a long time feel that this is a development too many for Dereham. At some point we have to say enough is enough.'