While river pollution has been a persistent legacy of the industrial revolution, recent responses by two companies to two separate incidents indicate that corporate attitudes are changing.

A few weeks ago, anglers on the River Wandle in south London witnessed the distressing sight of thousands of dead fish drifting downstream. Within two days, after one-and-a-half tons of dead fish had been pulled out, directors of Thames Water admitted responsibility, saying it had been caused by a spillage of bleach from its Beddington sewage treatment plant.