For commuters at Greenford Tube station in west London, wading through floodwater on the way to work was an unwelcome daily reality. Sandbags were a permanent fixture. Nearby neighbourhoods lived with the threat of inundation after heavy rain. The council faced a daunting bill for engineering solutions — until a small team of unlikely engineers arrived and did the job for free.

Four centuries after beavers were driven to extinction in England, five of them were reintroduced to Paradise Fields — a 10-hectare former golf course in Ealing borough — in 2023. Conservationists, keen to demonstrate how "nature's engineers" could make London more climate resilient, secured a licence for the release along the stream running through the land. The Ealing Beaver Project was born.

The animals got to work immediately, reengineering the landscape with a series of dams that created a new lake almost overnight. They even dismantled an old dam built by volunteers and replaced it with a better one of their own. Within a year of arriving, they had bred successfully too, producing a litter. The transformation was remarkable.

"I just can't believe how much they've done in a short period of time — they basically said 'step aside, humans'," said Şeniz Mustafa, England's first urban beaver officer. "We do make things a little bit hard for ourselves. It goes to show that we don't have to use heavy machinery or build infrastructure, nature can do it."

The results speak for themselves. Even during periods of heavy rainfall, the area no longer floods. "When they put their minds to it, they really get things finished," Mustafa observed.

But the benefits extend far beyond flood prevention. The beaver-constructed wetlands have become a thriving ecosystem. In just 11 months, four new species have colonised the area: stickleback fish, dragonflies, damselflies, and the redpole — a bird that typically only stops off in England during migration. In a single month, 14 different species of butterfly were recorded. Tadpoles, freshwater shrimp, and toads have also returned.

"This diversity is great," said Mustafa. "None of that would have happened without beavers. It's interesting to see how other wildlife will just recolonise and return to a space."

The project is a collaboration between Ealing Wildlife Group, rewilding organisation Citizen Zoo, the Friends of Horsenden charity, and Ealing Council, with support from Beaver Trust and the Mayor of London. Mayor Sadiq Khan has committed to making London "at the forefront of the rewilding revolution."

For residents and the local community, the change has been profound. "The benefit to the local community is massive," said Mustafa. "They have completely transformed my perspective of what beavers can do." In an era of climate crisis, sometimes the most sophisticated engineering solution is a dam built by nature's original architects.