The longest river in England; flows eastward through London to the North Sea; Also called: Thames River.
River in S England; length 338 km/210 mi. The longest river in England, it rises in the Cotswold Hills above Cirencester and is tidal as far as Teddington. Below London there is protection from flooding by means of the Thames Barrier (1982). The headstreams unite at Lechlade.