Palaeography and Diplomatic provide the necessary expertise for the study and interpretation of official documents. Palaeography, however, has a broader significance, since it extends beyond official documents to include the whole range of manuscript material which has survived from previous centuries, whatever its context.

Palaeography is the study of old handwriting, with the primary aim of learning to read it, but with further more subtle purposes, as indicated above.

Diplomatic is the study of the form of official documents, considering both "external" and "internal" characteristics, and especially the standard formulae common to particular categories. The general purpose is to achieve correct interpretation but, as with Palaeography, Diplomatic involves a range of skills.

The main collection is located in the Thomas Parry Library. Some duplicate items are housed in the Hugh Owen Library on level F.