Rare water voles, made famous by Ratty in the children's classic Wind in the Willows, appear to be making a comeback along one river, a survey has revealed.
Large numbers of voles have been found on the River Lee Navigation
The mammals, now one of the UK's most endangered species, have been hit by development and have being preyed on by non-native American mink.
Their numbers have declined by 90% in the past 10 years.
But a survey has found unexpectedly large populations of voles on the River Lee Navigation at Cheshunt, Herts.
The survey was conducted by British Waterways and Hertfordshire and Middlesex Wildlife Trust.
Improved habitats, including the installation of soft banks, are behind the resurgence, said Leela O'Dea, an ecologist for British Waterways London (BWL).
She added: "Water voles were once common along our canals and rivers but their numbers have been decimated in the last 30 years. Identifying where they live is crucial to their survival.
"We were delighted to find evidence of hotspots at King's Mead and Silvermead nature reserves and on the Navigation itself near Cheshunt."
Kenneth Grahame's 1908 novel Wind in the Willows depicted a life spent "messing about in boats" in rural England with laid-back Ratty, the star of the piece.