Beavers, which were hunted to extinction in Britain in the 16th century, are making a comeback and in the process are helping to restore valuable wetland ecosystems. Known as nature's engineers they restore wetland habitats through dambuilding and felling trees, slowing, storing and filtering water in their habitat, which attracts other wildlife and reduces flooding downstream.

In the UK, 90% of wetland habitats have been lost over the last 100 hundred years. These waterlogged environments are rich in biodiversity and the loss has led to a drastic decline of wildlife. They are also important in countering the effects of extreme weather conditions, storing and absorbing the water flow during floods and storms.

Guy Henderson heads to Devon to see beavers flourishing in English rivers. Derek Gow, a key figure in rewilding beavers, shows the difference they have made to his land. As the former farm was being transformed, Gow also introduced a number of other lost British species, turning it into a biodiversity hotspot. Recent changes to legislation mean the beaver now has protected status in England as it does in Scotland and elsewhere in Europe.