The older a heritage asset is, and the fewer surviving examples of its kind, the more likely it is to have special interest.
Age will relate to heritage assets surviving from the earliest phases of development through to and including the 20th century. Generally, heritage assets surviving in this category will be a good example of a building/site/structure etc. type and surviving in or closely to their original form. Local Heritage that has undergone superficial alterations that may be reversed for example, reinstatement of timber windows will not necessarily be excluded from recognition. The age range can be adjusted to take into account distinctive local characteristics or building traditions in an area i.e. commercial, industrial or post-war buildings and areas of later expansion.
Does it remain in a coherent and recognisable form?
Does it retain its historic features and layout?