- In the Country of My Enemy
- The Foundations of Modern Wales, 1642-1780
- The Death of an Employer
- The Welsh Language 1939-1970
- Jobs for the Boys: The History of Nepotism in Wales
- Languages and Nations: Nationalism and the Cultural Object in the Nineteenth and Twentieth Centuries
- Languages and Communities in the Celtic West: Historic and Comparative Perspectives
- The Welsh National Language Survey: A Report
- The Welsh Language Today
- The Origins and Early Development of the Welsh Comprehensive Schools
- The English Language in Wales
- The Development of the Welsh Language from 1979-1988