Negligent profiteer Thames Water was hit with a £250,000 fine yesterday for allowing gallons of raw sewage to ooze into an idyllic nature reserve.

Fish and other water wildlife were found dead during the incident at the National Trust’s 143-acre Chase site — the third in six years.

Managers at the site in the North Wessex Downs area of outstanding natural beauty had only just completed a two-year habitat rejuvenation project to increase the range of wildlife.

But the shady woodland brook turned into a killing ground when Thames Water failed to dispatch engineers after alarms signalled blocked pumps at the nearby Broad Layings sewage station.

Environment Agency officer Matthew Rice recalled that the 2012 incident saw an entire 600-metre length of the brook and a nearby pond had been polluted with high levels of both ammonia and e-coli.

Judge Recorder Arbuthnot ruled Thames Water, which made £346.7 million in profits last year, negligent and said a £250,000 fine was proportionate.