The Breviary of Britayne is in Tudor Books.
[11th December 1282] Untill that the prince him selfe, beyng forsaken by many of his owne men: was by the men of Buelt betrayed, not far from the river Vaga, or wye, whether he came with a very few souldiers. And by one Adam Francton, whiche faught under the conduct of Helias walwin: far from the residew of his owne power beynge accompapnied with one only Page, and unarmed, with certain other noble men of that country, tolde ye same before to his enemies: was there slayne most dishonorably.