British Rivers - A Working Classification
According to Lewin (1981) the six largest rivers in Britain are shared between Scotland, Endland and Wales. The Thames is the longest, and has the greatest catchment area. It is followed by the Wye and the Severn in terms of length and the Trent in terms of catchment area. For shear volume of water flowing through the system, the Thames is no match for the mighty Tay and Tweed in Scotland.