A known problem for proponents of Entity Linking in Cultural Heritage collections is the poor representation of entities in popular knowledge bases such as DBpedia. This is largely due to the niche nature of the entities contained in these collections. Where such problems arise it may be possible to generate more complete knowledge bases from existing resources used by scholars who specialise in the domain of the collection in question. This paper presents the process by which a knowledge base for informing an entity linker about people in Irish cultural heritage collections was developed from the Dictionary of Irish Biography, a compendium of biographies about notable Irish figures written by Irish historians. We present the design considerations which influenced the structure of the knowledge base given its intended application and the process by which the desired information was extracted from the collection of biographies. This includes the description of an automatic linking process for associating entities in the new knowledge base with their corresponding entries in DBpedia where such a correspondence was possible. We discuss other resources which possess similar properties to the Dictionary of Irish Biography that may be useful for expanding the current knowledge base. A preliminary test on a collection of Irish manuscripts is conducted using an existing Entity Linking tool to demonstrate the use of this knowledge base in a linking task.