Relates principally to Matson's effort to locate official records and manuscript material about the Nandi and neighbouring groups with government officials serving in various districts, officials who served in Nandi previously, missionaries, settlers, and representatives of various libraries and archives. Subjects also include Matson's efforts to secure official support for his research. However, with Matson's return to England in late 1963, the correspondence includes fewer official contacts and more with scholars and students. The subjects also broaden progressively to include various aspects of Kenyan history.

Matson received an increasing number of enquiries from students; those with whom he had been in contact in earlier years moved into more senior positions and continued to correspond with him on points of Kenyan history.

Correspondents include: