The rodent was discovered along the River Wensum at Pensthorpe Natural Park, near Fakenham, last year, in a discovery heralded as a landmark moment for the species.

It was the first time a beaver had been found living free in Norfolk since the animals became extinct five centuries ago.

But locals speculated it likely came from a licensed enclosure at Sculthorpe Moor Nature Reserve, about three miles upstream.

The Sculthorpe Moor Nature Reserve (Image: Ian Burt)

Beavers have been released elsewhere in Norfolk but the two other locations, near Heacham and Holt, are much further away and would have required the beaver to travel across roads and farmland.

However, the Hawk and Owl Trust, which manages the Sculthorpe site, insists none of its beavers have escaped from its reserve.

A spokesman for Natural England said workers are still investigating where it came from and that one possibility they are exploring is that it escaped from a licensed enclosure.

Beavers have been reintroduced in parts of the country in the hope that they will help provide a natural food management through building dams.