A draft tract entitled 'Proofes drawne from authorities and other reasons why Cadelh prince of Southwales was the eldest sonne of Roderic the greate (kinge of Wales) and that he and his issue after him had a superioritie over the rest of Wales and his two bretheren and the descendantes from them' by, and in the autograph of, Robert Vaughan of Hengwrt. The substance of this tract was subsequently incorporated in Vaughan's British Antiquities Revived (Oxford, 1662). The volume contains both the arguments and answers set forth by Vaughan and therefore differs considerably from Peniarth MS 277 which contains only the arguments.
Pasted inside the front cover is a short description of the volume in the form of a cutting from Messrs. Sotheby, Wilkinson and Hodge’s Sale Catalogue of the Mostyn Library (1919), p. 22.