PPS 6 Planning Archaeology and the Built Heritage·Page 48·C4
Age and Uniqueness as Listing Considerations
Age and uniqueness are important factors for listing, particularly for buildings nominated on historic interest grounds, with buildings before the early 19th century generally being more likely to qualify.
Age and uniqueness are important considerations, particularly where buildings are proposed for listing on the strength of their historic interest. The older a building is, and the fewer surviving examples there are of its kind, the more likely it is to have historic importance. In general buildings dating from before the early 19th century,
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/PPS 6 - Planning Archaeology and the Built Heritage.pdf