A composite manuscript of loose papers and fragments of manuscript volumes. It contains poetry and prose, mostly in Welsh, much of the poetry being addressed to the Owen family of Brogyntyn and Clenennau and other related families. Apart from a late-sixteenth century awdl by Wiliam Llŷn (ff. 57-58), the other items all belong between the first half of the seventeenth century and the first half of the eighteenth century.
Fragments apparently once part of books, some of which perhaps were never bound, are: a narrow folio of cywyddau and englynion by Mathew Owen, in the hand of Nathanael Jones (ff. 20-26), written not before 1656 (see ff. 24 verso-25), with autograph englynion added by Harri Howel (f. 20 verso) and by Nathanael Jones (f. 20 verso, 23); a folio manuscript containing cywyddau to Lewis Anwyl of Parc and his family, dated 1627-1636 (ff. 38-55), written by two good hands of the first half of the seventeenth century, one responsible for ff. 38-50 verso, the other ff. 51-55; a quarto manuscript with transcripts of poetry of the Gogynfeirdd (ff. 113-122; paginated 1-20), by a seventeenth-century hand similar to that of Morris Evans (cf. ff. 93-94, 123-141); pedigrees of Welsh royal lines, the Maurices of Clenennau, etc., in English (ff. 123-141; original foliation 1-12 survives), in the hand of Morris Evans (ff. 123-127 verso, 129-134 verso) and a second hand (ff. 128 recto-verso, 135-141); a narrow folio of canu brud attributed to Myrddin, Taliesin, etc. (ff. 178-186), written by Nathanael Jones, not before 1651 (ff. 182 verso, 183 verso 'aetatis suae a 21o Feb: 1650 27'); a folio manuscript of canu brud, mainly cywyddau, by Dafydd Llwyd and others (ff. 189-207), in a poor hand of the mid seventeenth century, probably that of Thomas Edwards to judge by pentrials on f. 196 verso, who refers to Tregeiriog (f. 199 verso) and 'Llanfylling fairings' (f. 207 verso); an octavo manuscript containing poems by Robin Clidro, etc., in a seventeenth or eighteenth century hand (ff. 210-219); and a folio manuscript of autograph cywyddau and englynion by Huw Morys, some addressed to William Owen and Sir Robert Owen (ff. 222-226 verso). Poetry written on loose papers includes autograph poems by Huw Morys (ff. 12-18), John Owens (ff. 59-71; f. 69 recto-verso may be his italic hand), Harri Howel (ff. 75-76 verso, 90 recto-verso), Owen Gruffydd (ff. 84-89, 230-231), William Phylip (ff. 97-98 verso), John Morgan, later vicar of Conwy (f. 101 recto-verso, the poem incomplete and anonymous, dated 1688, the hand his), Siôn Rhydderch, 1732 (ff. 104-105, 227-228), and Edward Lloyd, Brewis (f. 221 recto-verso). There are probable autograph poems by Edward Rowlant (ff. 72-74 verso, 79-80) and John Richard (f. 81), and possible autograph poems by 'J. Ll.' (f. 26 verso), Mathew Owen (ff. 77-78, 232 recto-verso), Siôn Roberts (ff. 91-92), Huw Cadwaladr (ff. 106-108) and 'R.C.' (f. 163). Other poetry is in the hands of Morris Evans (ff. 93-94) and 'Theo: Ro:' (ff. 152-154 verso). Also included is a letter, 1652, from the antiquary Meredith Lloyd to Thomas Vaughan, the alchemist and poet (ff. 1-3 verso), followed by a copy of Hanes Taliesin (ff. 5-10 verso). The 'Cywydd Marwnad i Mr William Owen o Borkynton' by Huw Morys, beginning 'Mae gwaedd oer lem Gweddw [yw'r wlad]', discussed in E. D. Jones, 'The Brogyntyn Welsh Manuscripts', National Library of Wales Journal, 7 (1951-2), 165-198 (pp. 186-189, 196-197), has not been found.