We've seen this happen in the Craven District of CPRE.
Planning permission on this site (hotly objected to by residents and local groups) was granted based on quota of much needed affordable homes.
Developers then applied to reduce the number of affordable homes because financially, they couldn't afford to build them....
The same developer did this in Settle at the site behind the Falcon Hotel.
When will fair play and common sense be a key part of the planning process?