His cywyddau to Gwilym ap Gruffydd of Penrhyn , Sir William Thomas of Raglan , and William Fychan ap Gwilym of Penrhyn , can be dated fairly easily. No poem by him to Owain Glyn Dŵr has been preserved, although there are suggestions in his poems to members of the Penrhyn family that his sympathies were with the adherents of Glyn Dŵr . Even if he did sing to the prince's adherents, it was more discreet for their sakes, in the time of oppression which followed in the wake of the war, not to give them prominence. His cywydd to Beuno is interesting; of still more interest is his bardic ‘controversy’ with Llywelyn ap y Moel and his reply to Siôn Cent 's (q.v.) satire on ‘ Yr Awen Gelwyddog ’ (‘the lying muse’). His cywydd to a beard is also in the bardic tradition but it contains no chronological references. One must distrust the authorship of the cywydd ‘i'r Faslart’ because of the reference to Powys contained in it, the same applies to the cywydd to Sir Gruffydd Fychan , and for the same reason — and because of the uncertainty of the manuscripts on the matter. The same is true of the cywydd urging a fox to kill Dafydd Nanmor 's peacock; his satiric awdl to another fox (‘ Madyn Iwynogyn ’) can, however, be regarded as authentic.