The four criteria for determining class importance apply to Saxon shore forts as follows:

Period (currency): Restricted. The Saxon shore forts were all constructed during the 3rd century AD, probably between c.225 and c.285 AD. Coin and pottery evidence suggests that the majority continued to be occupied until the later 4th century AD, and at least one, Richborough, continued to be occupied until the earlier 5th century AD.

Rarity: Very rare. The remains of nine Saxon shore forts are known in England, all located in south-east England on the coasts of Norfolk, Essex, Kent, Sussex and Hampshire, with a particular concentration in Kent.

Diversity (form): High. Using shape as the basic discriminating criteria, at least five tgroup of square "type" Saxon shore forts so defined may be further divided into two distinct chronological groups, earlier 3rd Century and later 3rd Century, making at least six types in all.

Period (representativity): Medium. Saxon shore forts are one of many classes of Roman monuments and one of several classes of Roman military monuments recognised in England. However, they are located in a part of England where very few other Roman military sites have been discovered and they are highly representative of the increasingly defensive military strategy of later Roman Britain, and of a particular set of circumstances prevalent in south-east England at that time.

Assigning scores to these criteria following the system set out in the Monument Evaluation Manual, Saxon shore forts yield a Class Importance Value of 33. This lies more than halfway up the range of possible values (max. = 64). In selecting examples of national importance, attention needs to be given to including examples of all types, which together exhibit the full range of variable characteristics of the class.