writes in The Place-names of Hertfordshire (1904):

Others, however, consider it more likely that the Knights Templar used a name already in use, particularly since the location was already a crossroads. In addition the settlement was already thriving as a late Anglo-Saxon part of Weston. Alternative etymologies have been suggested, including Middle English balled, meaning "bald", together with Old English ac, meaning "oak" (the site may have been identified by a large old tree near the Anglo-Saxon graveyard or where the Templar church