I have not accessed this work but must just point out that the book's very title encapsulates a fundamental misuse of terminology, namely the word 'saga'. A' saga', in its proper meaning as applied to Germanic and Old Norse literature, means a PROSE story or narration, such as for instance the Icelandic family sagas, the Icelandic sagas of kings, the fornaldar sogur (sagas of old times), etc. No heroic prose has survived in Anglo-Saxon, only saints' lives and similar material.
Such heroic material as survives in Anglo-Saxon, such as the heroic poem Beowulf, the Finnsberg fragment, the Battle of Maldon, etc is in the form of alliterativeverse, not prose sagas. Clearly, all the Germanic ethnic groups shared a common heritage of the heroic age of Migrations, but no Anglo-Saxon sagas have survived, and we do not know if any ever existed or were written down. Starkad, for instance, is a character appearing in old Norse sagas and poetry.