- Drafts and notes for articles and lectures by T.J. Owen, on the history of the manor and parish of Aber, Caernarfonshire.
- Photocopies and transcript copies of original documents, 14th -19th century, and maps and photographs relating to Aber.
- Also contains correspondence between T. J. Owen and archivists at the County Record Office, Caernarfon, the PRO, the librarian of Hatfield House, and county council officials. Mainly relates to Aber manor history and parish affairs.
- Material relating to the life and work of Hugh Davies (1739-1821), botanist and parson.
- Research material relating to the Thomas family of Pen y Bryn, Caernarfonshire.
- Notes on charities in the parish of Aber.
- List of rectors of the parish of Aber, 1284-1888.
- Photograph album, biographical material on the Palgrave Simpson family, Norfolk, ancestors of Mrs. T. J. Owen. Includes Palgrave Family Memorials, edited by Charles John Palmer & Stephen Tucker, produced for private distribution, Norwich (1878).