The days when Lord Nelson fished the Wandle for its world famous trout are set to return thanks to the hard work of schoolchildren from across Merton, Sutton, Wandsworth and Croydon.

For the first time in more than 200 years, the river’s trout population is believed to be naturally increasing following the success of the Wandle Trust’s Trout in the Classroom project.

Pupils from 19 primary schools have been releasing trout fry - grown in aquatic hatcheries placed in classrooms - into the Wandle, the latest cohort of young volunteers taking part in the project which started in 2002.

And according to Gideon Reeve of the Wandle Trust, the trout are now here to stay thanks to their hard work.

He said: “It’s always been quoted Lord Nelson used to fish in the Wandle when it was famous across the country for its trout.

“But because it’s so fast flowing it became fantastic for industry and soon there were 90 mills along the river bank helping produce every type of product you could imagine.

“This put more and more pressure on the Wandle and the last of the dying trout was seen in 1934. By the 1960s it was even considered a sewer.

“Yet over the last three or four years there has been evidence of the trout not only surviving, but more recently, producing their own offspring.

"It’s incredible news and is all down to the hard work of school children from all across the Wandle valley.”

Each school taking part in the programme was given 200 trout eggs in January, kept in a tank cooled using beer chillers.

Now the trout fry are about two inches long, they have to be released into the river, with schoolchildren helping let the fish go.