Place-names are used to communicate Traditional Ecological Knowledge (TEK) by all indigenous, aboriginal and First Nations people. Here and for the first time, English place-names are examined through a TEK lens. Specifically, place-names formed in Old English—the language of the Anglo-Saxon—and coined between c. 550 and c. 1100 A.D., are explored. This naming horizon provides the basic name stock for the majority of English towns and villages still occupied today. While modern English place-names now simply function as convenient geographical tags Old English toponymy is shown here to exhibit close semantic parallels with many other indigenous place-names around the world. Seeing Old English place-names as a hitherto unrecognized and unexploited repository of TEK may have exciting and important consequences. By identifying the climatic and meteorological correspondences that can be drawn between the period of place-naming and the present day, this paper explores how early medieval water and woodland names might offer new perspectives on, and perhaps solutions to, flooding, the most serious environmental threat currently facing the UK.