In some manuscripts ‘ Cneppyn Gwerthryniawn ’ is given as one of several nicknames borne by Sypyn Cyfeiliog or Dafydd Bach ap Madog Wladaidd (q.v.) , but as this Dafydd sang late in the 14th cent. he could not have been the original Cneppyn (see I.G.E. , 1925 ed., clxvii et seq. ).

In Cardiff MS. 38 , a manuscript containing the ‘ Pum Llyfr Kerddwriaeth ’ (the Welsh medieval ‘ars poetica’) in the hand of William Cynwal (q.v.) , and also in other 16th cent. copies of the same work, ‘ Cnypyn Gwerthryniawn ’ (or Gwerthryniawc ) is mentioned as a grammarian , and his name precedes that of Dafydd Ddu Athro (q.v.) . As the bardic grammar was based on Donatus , this fits in well with the statement by Gwilym Ddu , and suggests that the leading poet-teachers were in possession of a written grammar in Welsh as early as the 13th cent. if not earlier (see G. J. Williams , Gramadegau'r Penceirddiaid , xx-xxi).