www.dailymail.co.uk/news/article-1208457/The-Wider-View-Surfing-swell-Severn-Bore.htmlAs I recall, the first person ever credited with surfing that river was a gentleman by the name of Mad Jack Churchill who learnt to surf in Australia after WW2.
However I think his main claim to fame was that while he was serving in Europe during the war, he had the distinction of capturing a significant number of german prisoners armed with nothing more than a Claymore.
For the uninitiated, a Claymore is a dirty big sword.