'A Neglected Revolution Family. The Lancashire Lords Willoughby of Parham and their Association with Protestant Dissent' by Philip J. Willoughby Higson (PhD thesis, University of Liverpool, 1969), FRSA. Typescript.
An account of the lives and careers of the 1st-5th Barons Willoughby between 1640-1765, and their connection with religious dissent, politics and education. Seven volumes:- Vols. I, II. Thesis, with bibliography; Vols. III-VII. Appendices (12) consisting of edited correspondence, legal and economic material, pedigrees, etc., maps and plans, and many photographs. See A.J., 52 (1972), 169-84 (account of Hugh, 5th Baron Willoughby, PSA).