Four hundred years after beavers in England were hunted to extinction, a European beaver has set up home on the Thames outside Oxford.
The beaver has offered the clearest proof that the species can survive in the Oxfordshire countryside, by living in the wild throughout the winter.
The creature was not released as part of a wildlife experiment - it is thought to have escaped before Christmas and has managed to evade capture for more than three months.
The Oxford Mail this week discovered the location of its secret river home and contacted the Environment Agency.
The EA said a Gloucestershire-based wildlife group, which breeds beavers in captivity, has been called in to trap the beaver. The agency asked us not to reveal the location of the beaver's lodge to avoid it being disturbed or harmed.
There have only been a handful of sightings, with one local resident claiming to have seen it running across her garden.
Graham Scholey, of the Environment Agency, said: "Conservation staff can confirm the presence of a beaver living wild on the Thames.
"Evidence included a number of young willows which had been felled on the riverbank in the characteristic fashion of a beaver.
"They do this to feed on the young shoots and bark at the top of the trees.
"This beaver has escaped from captivity, although the source is currently unknown. Measures are at hand to recapture the beaver, and its location is not being disclosed to ensure that this operation can take place with minimal interference and stress to the animal. "
Whereas the American beaver can be destructive, environmentalists say the European species would be a force for good, even helping to keep rivers clear of debris.
And Mr Scholey moved to dispel fears that the beaver's famed dam-building abilities could increase the risk of flooding.
"The European beavers are capable of building dams. But it is clear that this beaver has been living largely unnoticed. It has not built any dam structures, which are more typical of the Canadian species."