IT seems most improbable that land earmarked for Derwenthorpe would ever merit the status - and the maintenance costs - of a nature reserve. Rather, we are doing our best to ensure the development is a model of sustainability.

Our adviser, Professor Chris Baines - awarded the prestigious RSPB Medal - believes we can achieve this. The Environment Agency and English Nature have no objections to the project.

And 100 per cent of the perimeter hedgerows and trees, two-thirds of the internal hedgerows - including those alongside the cycle path - and 100 per cent of these of high value in wildlife terms, will all be retained.

If the 540 homes, including about 200 affordable homes, had to be built in other parts of the city other people in other places would raise objections too. Concentrating development here provides the chance for a properly planned new community, mostly of houses with gardens rather than flats.

Other correspondents have pointed out that the council could make more money selling the land to a private developer. The council has never denied this. It wants a scheme of higher quality - with superior "eco" standards, more accessible design, pedestrianised home zones and better public space - which we are providing.

These extra features add costs which affect the land value. If the project creates profits, these go in the first instance to the council and, after a certain point, will be split between the two parties. We have already agreed to plough back any profits, first to bring up the affordable housing from 35 per cent to 40 per cent and thereafter for other work for the benefit of York.

Richard Best,

Director, Joseph Rowntree Foundation,

The Homestead,

Water End,

York.

Updated: 11:20 Tuesday, May 24, 2005