PPS 21 Sustainable Development in the Countryside·Page 22·Policy CTY 3
Non-listed Vernacular Dwellings: Restrictions on Future Replacement
Where the original vernacular building is retained, it cannot be replaced again. The policy does not apply where permission for replacement was previously granted with conditions restricting the original building's use, or where the building is immune from enforcement action.
In cases where the original building is retained, it will not be eligible for replacement again. Equally, this policy will not apply to buildings where planning permission has previously been granted for a replacement dwelling and a condition has been imposed restricting the future use of the original building, or where the building is immune from enforcement action as a result of non-compliance with a condition to demolish.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/PPS 21 - Sustainable Development in the Countryside.pdf