Chris 11.28 - you are mixing issues and it is hard to know what you are talking about.
I take it you are talking about my comment elsewhere about the DCLG guidance document on housing needs assessment? I already said that it is not related to this discussion thread, but I will explain since you have raised it again (apologies to others).
The DCLG have produced a 102 page guidance document explaining how housing need should be assessed. The evidence of local housing need is used when considering planning applications to build on rural "exception sites". These are sites outside the development boundary where development would normally be prohibited by planning rules, but they can be used as an exception to normal constraints if there is a compelling local need for housing that can not be delivered in a less environmentally harmful way (e.g. there are no other sites within the development boundary).
A proposal was made to build affordable housing on a site in the AONB outside the village where I live, and the evidence of the local housing need was produced by the housing association making the proposal. The figures they presented were a joke, and the method they used to produce them was not consistent with the DCLG guidance.
The housing association claimed that their method was standard practice. I complained to the TSA about it, and the investigation concluded the same. I therefore studied over 100 rural housing needs assessments that had been produced all over the country to support exception site developments. Only one survey correctly followed the DCLG guidance.
99% of the studies used an incorrect interpretation of one badly written sentence in the DCLG guidance document to produce a grossly exaggerated figure for the local housing need. I drew the DCLG's attention to this incorrect sentence and asked them to correct it so that it could no longer be misused as it currently is being misused. They refused to correct it because they said their own investigation had showed no indication that it was leading to widespread errors in housing needs assessment.
This is a case of putting the telescope to a blind eye and saying "I see no ships". The DCLG is behaving in a completely unobjective way and is ignoring the documentary evidence I have submitted to them proving there is widespread exaggeration of the level of local housing need purely to justify developments that should not otherwise be approved.
apologies for others who are probably not interested in this ...