It may have been that Hereric had been poisoned by his hosts and Edwin of Northumbria invaded in retaliation; or perhaps Edwin himself had Hereric poisoned and invaded Elmet to punish Ceredig for harbouring him.
Puido ser que Hereric fose envelenado polos seus anfitrións e Edwin de Northumbria invadise por vinganza; o use cadra o mesmo Edwin envelenou a Hereric e invadiu Elmet para castigar a Ceredig ap Gwallog por telo cobixado.