Housing developers are using a legal loophole to dodge building affordable homes across the south west's countryside, according to data from Shelter and the Campaign to Protect Rural England (CPRE).

The research has been released ahead of a speech on Monday, 5 March by Sajid Javid, the Secretary of State for Housing, Communities and Local Government, where he is expected to outline reforms to national planning rules.

The national research included 13 developments in the south west where viability assessments were being used. These developments provided 1,675 homes in Cornwall, of which 40 per cent were required to be affordable. However, developers used the ‘viability loophole’ to reduce their quota by 35 per cent – depriving the local residents of 232 affordable homes.

Janette Ward, CPRE south west chair, said: “All across the south west region, viability assessments are being used by developers to reduce the number of affordable homes.

"For example, an extreme case on the edge of Gloucester with a strategic housing allocation for 420 homes has gone ahead on appeal with no affordable housing whatsoever.

“This is distorting rural communities and leaving younger people and those on lower incomes unable to find good homes in rural areas.”

Looking at eight rural councils over one year, the analysis showed that half the affordable homes that councils were required to build were lost when viability assessments were used

The charities say that developers use viability assessments to argue that building affordable homes could reduce their profits to below around 20 per cent, allowing them to cut their affordable housing quota.