The poem had once been considered a near-contemporary authority, but Michael Lapidge has shown this to be based on a misunderstanding of William's reference to "a certain obviously ancient book".
Poemu se nekad smatralo mjerodavnim izvorom koji je blizak onom vremenu, no Michael Lapidge je pokazao da se to temelji na tome što se nije razumjelo Vilimovu referenciju na "određenu očigledno staru knjigu".