In April a pair of white storks built a shaggy nest of sticks in the top of an oak tree in the middle of our rewilding project at Knepp estate in West Sussex. Drone footage, taken before the pair started sitting on them, showed three large eggs. The last definitive record of a pair of wild storks successfully breeding in Britain was in 1416, from a nest on St Giles Cathedral in Edinburgh.

No one knows why storks disappeared from our shores. They often feature on the menus of medieval banquets so we might, quite simply, have eaten them out. But there could be a more ominous reason. Early spring migrants, nesting on rooftops and happily associating with humans, storks have long been a symbol of hope and new life – hence the fancy of storks carrying babies in slings in their beaks. Yet their association with rebirth also meant they became a symbol of insurgency. Shortly after the restoration of King Charles II in 1660, with storks rare but clinging on, parliament debated putting greater effort into expunging them from the east of England for fear they might foment republicanism.

The young storks in our oak tree are part of a project, inspired by successful reintroductions elsewhere in Europe, and involving two other sites in East Sussex and Surrey, to return this species to Britain. Imported from Warsaw Zoo in Poland in 2016, they have spent the best part of three years in a six-acre pen with a cohort of juveniles and several injured, non-flying Polish adults. The fact that the pair’s eggs were infertile and did not hatch by the end of May was not too disappointing. They’ve since been scavenged by rooks or raptors when the pair stopped sitting on them. They are only four years old, and storks can live to over 30, with their first attempts to breed often failing. Prospects for next year are encouraging. They are up there in the oak, even now, bill-clattering, mating and displaying. Other birds have already shown strong loyalty to the site. Two years ago, a young Knepp bird flew across the Channel to France and, this summer, returned to the pen to rejoin its mates.

In the face of reports of unrelenting ecological loss (the UN estimates a million species are on the brink of extinction globally), the white stork’s return is refreshing news. As tens of thousands march about the climate crisis and eco-anxiety besets us, these glimpses of restoration are important. Featuring the storks in BBC’s Springwatch in June, Chris Packham described the project as “imaginative, intelligent, progressive and practical … this is proper conservation done properly”. The stork, with its links to insurgency and rebirth, might even be the perfect emblem for Extinction Rebellion.

And yet its path to restoration in the UK has not been smooth. Support from conservation bodies has been surprisingly difficult to come by, some hard-pressed with their own initiatives; others simply reluctant to stick their necks out. A joint application with the Sussex Wildlife Trust for lottery funding – which would have secured £1m for schools and community engagement – was kiboshed by the trust’s own conservation committee just after the project was announced as a finalist. The committee raised doubts about the stork ever having been a British bird, had concerns that English-bred birds would migrate across the Channel, and feared that their messy nests and proximity to humans would cause a hazard, including unwanted debris down people’s chimneys.

Up stepped the Durrell Wildlife Conservation Trust, a charity whose mission to “save species from extinction” has won worldwide acclaim, only to be told that at the time of application it did not meet the lottery’s criteria. Ultimately, the project has had to rely on private individuals building introduction pens and feeding the birds at their own expense, and the expertise of tiny yet determined conservation organisations such as the Roy Dennis Wildlife Foundation – responsible for the successful reintroductions of ospreys and white-tailed eagles to Britain – and Cotswold Wildlife Park, which quarantined the original Polish birds and continues to manage and cover the costs of the captive breeding programme using its own staff and facilities.

Storks in their nests on prefabricated posts in Extremadura, Spain. Photograph: Jorge Rey/EPA

Across Europe, as fatalities from power lines and roads have increased, and populations have suffered from the draining of wetlands and disappearance of insect-rich pastures and meadows, the loss of storks has been felt deeply. A few years ago, a tearful old woman in a village in Belarus showed me the nest on her roof empty of storks for the first time in living memory. Where storks have been reintroduced, they are greeted with delight and the restoration of historical stork festivals. The Spanish erect poles for nests along their motorways and in Alsace householders install cartwheels for storks on their roofs. During a cold snap in Bulgaria last March, villagers sheltered white storks in their homes.

A driving inspiration behind the project in the UK is the hope that the storks’ return will spark similar feelings of empathy and affection here. Bill-clattering from their nests on rooftops, churches and town halls, they might also induce concern for the wider countryside where they fly off to feed on earthworms, grasshoppers and frogs. White storks could be that charismatic species that connects urban communities directly with landscape restoration. Certainly, people once loved them here. Our local village, Storrington, was originally “Estorcheton” or “home of the storks”. And the public response has been overwhelming, with people flocking to see white storks flying free in England for the first time in hundreds of years, and private landowners queueing up to offer more introduction sites.

The flight of the white stork over Britain seems to articulate perfectly the public desire for ecological change and regeneration; it is the triumph of the bigger picture over bureaucracy, self-interest and negativity; a beacon of hope in a world that, too often, drags its heels.

• Isabella Tree is the author of Wilding: The return of Nature to a British Farm, charting her rewilding project. The White Stork Project is raising money to help monitor the storks in the wild and engage the public