The first-ever bathing spot on the River Thames in London is among 13 new sites to open on Friday as the official bathing season begins. Across the season , until September 30, 464 sites across England ’s coasts, rivers and lakes will be subject to regular water quality testing to give people a better idea of the state of the water they are swimming, paddling or enjoying water sports in. The site at Ham and Kingston becomes the first on the river in London to have the designated status, as of Friday. It marks a milestone moment for improved water quality in the river, which had been declared biologically dead in the 1950s because of pollution. Other new spots include the filming location for TV drama Broadchurch, popular beaches, a meadow and river site in the area that inspired The Wind In The Willows, as well as a spot in Yorkshire where the River Swale flows in waterfalls over limestone steps.…