Extensive coastal lowlands known as Levels border the Severn Estuary and Bristol Channel in southwest Britain. The Levels are the result of many years of salt marsh reclamation, apparently initiated during the Roman Period, through a programme of sea bank construction. The altitude of the Levels is typically between 5-6 m Ordnance Datum (OD), an altitude that is below the current Mean High Water Springs level in the Severn Estuary. Therefore, the Levels are vulnerable to flooding, not only from river sources, but also from the sea at times when sea banks are overtopped and/or breached. A number of significant historic coastal flooding events have affected the Levels, but the event attributed with causing the greatest devastation occurred on 20th January 1607, and is the subject of this study. This flood event is often cited as being caused by a storm, alternatively however, we consider that some evidence suggests that the flood may have been the result of a tsunami, and that a reassessment of the cause is required. In this note, our intention is to discuss the existing literature, whilst results from our recent fieldwork in the area will be prepared for future publication.