Britain’s biggest conservation charity has signed up to i’s manifesto to Save Britain’s Rivers and called on all the main political parties to back it in full.

With 5.7 million members from across the political spectrum, the National Trust’s intervention adds to the pressure on Labour and the Conservatives to sign up to the pledges to protect Britain’s rivers from sewage and other forms of pollution.

As one of the UK’s largest charities, the National Trust has significant influence over nature policy and the conservation of Britain’s green spaces and heritage sites.