 Historians are agreed that the introduction and conclusion were added by a different author than that of the Libellus. Who that was, however, is open to debate. The historian C. W. David felt that it was based on the work of the chronicler Symeon of Durham, which thus made a credible date for the creation sometime between 1109 and 1129. David also felt that the Vita was used by a later work of Symeon's, the Historia Regum. Offler, however, felt that although Symeon knew of the Libellus, there was no evidence that he used the Vita, which would leave the author of the Vita unclear.
