The dip itself was made by ice. Where Hadrian's Wall rides the edge of the Whin Sill between Milecastle 39 and Crag Lough, melting glacial water carved several sharp depressions into the cliff line. The sycamore stood in one of these, with the wall and the cliff rising dramatically on either side, framing the tree in a kind of natural amphitheatre. The tree itself was a non-native sycamore, Acer pseudoplatanus, planted in the late nineteenth century by John Clayton, the Newcastle lawyer and antiquarian who spent fifty years excavating Hadrian's Wall every summer. By the time Clayton died in 1890 he owned five Roman forts and roughly twenty miles of wall, which he protected from farmers quarrying the stone. He planted the sycamore as a landscape feature. He could not have imagined what it would become.

In 1991, Kevin Costner's Robin Hood: Prince of Thieves shot a scene near the beginning of the film at the gap, despite the fact that the actual Sherwood Forest sits 170 miles to the south. The tree became 'the Robin Hood tree' to a generation that had never read Walter Scott. In 2003, a helicopter filming a David Attenborough series crashed about 30 metres from the trunk, narrowly missing the presenter Alan Titchmarsh; the tree itself was unharmed. In 2016 it won England's Tree of the Year. Over the decades it had become the backdrop for marriage proposals, weddings, and the scattering of loved ones' ashes. It was, by quiet consensus, the most photographed tree in Britain, and probably the most photographed single point in all of Northumberland National Park.

On the night of 27-28 September 2023, Daniel Graham, who ran a groundwork business near Carlisle, and Adam Carruthers, a mechanic living in a caravan in Kirkbride, drove through Storm Agnes to the gap. The cut was clean, made by someone who knew how to use a chainsaw, with a white line spray-painted on the trunk just below the blade. The tree fell directly onto Hadrian's Wall, damaging the stones. News spread before dawn. By morning, walkers were standing beside the stump in tears. The National Trust's regional director described public reaction as a wave of grief, partly because the tree itself was loved and partly because its destruction felt like an attack on something shared. Police described the felling as 'a deliberate act of vandalism.' The motive, when it eventually emerged in court, was harder to name than the crime.

Graham and Carruthers were arrested in October 2023 and charged in April 2024 with criminal damage worth £622,191 to the tree and £1,144 to Hadrian's Wall. Their trial at Newcastle Crown Court began on 28 April 2025 before Mrs Justice Lambert. Jurors watched mobile phone footage purportedly filmed by one defendant of the other carrying out the cut. On 9 May 2025, after five hours of deliberation, the jury found both men guilty. They were sentenced on 15 July to four years and three months in prison. Meanwhile, the stump did something nobody had predicted: it threw up basal shoots. By August 2024 new growth was visible. Cuttings have been propagated by the National Trust; the first seedling was presented to King Charles III, to be planted at Windsor Great Park. Further saplings are going to schools and national parks across the UK. The tree is expected to need 150 years to recover anything like its former presence. The wall it grew beside has stood for 1,900.

The Sill National Landscape Discovery Centre at Bardon Mill hosted an exhibition in 2024 built around a section of the fallen trunk. The 2025 Danny Boyle film 28 Years Later included a digital recreation of the tree, which Boyle said he hoped would be 'a wonderful tribute' to Northumberland's iconic sycamore. None of this brings back what was lost. The grief that followed the felling was disproportionate, by some measures, to the death of a single non-native ornamental tree. But the tree was never just a tree. It was a meeting point of geology and history and cinema and personal memory, a place where strangers had chosen to mark the most significant moments of their lives. The men who cut it down took something that did not belong to them and could not be replaced. The shoots returning from the stump are an answer of sorts. They are not, and cannot be, the whole answer.