The fens of East Anglia were once enormous — a vast, waterlogged basin covering much of Cambridgeshire and Norfolk. Agriculture drained nearly all of it. Today, only four wild fens remain in the Great Fen Basin area, and Wicken is one of them. The difference between the fen and its surroundings is immediately visible: the farmland outside has sunk as the drained peat compresses and oxidises, leaving the reserve elevated above the surrounding fields like a natural island. Wicken Fen's peat has been preserved by the water, and with it an entire ecosystem that elsewhere vanished over centuries of agricultural improvement. Walking along the boardwalk over the Mere, with sedge on either side and a reed warbler calling from somewhere invisible, gives a reasonable impression of what this landscape looked like in the medieval period — perhaps further back.

What makes Wicken Fen unusual among nature reserves is that it requires active management to stay wild. The sedge plant, Cladium mariscus, has been harvested here every year since at least 1414, when the first recorded sedge cutting took place. That harvest continues today, and the cuttings are sold for thatching roofs — the same use they served six hundred years ago. This matters ecologically: hundreds of species at the Fen depend on regular sedge clearance to maintain their habitat. Stop cutting, and the ecology shifts. The management of Wicken Fen is thus less about leaving nature alone than about recreating the ancient human practices that shaped it. Fen-working, peat-cutting, sedge harvesting — these are not just historical footnotes but conservation tools. The reserve is, in a specific sense, a collaboration between its present caretakers and everyone who worked the land before them.

Charles Darwin collected beetles here in the 1820s, before he sailed on the Beagle. He was a Cambridge student at the time, drawn to the fen as naturalists had been for generations. In the twentieth century, Sir Arthur Tansley and Sir Harry Godwin — the founders of modern ecology as a scientific discipline — used Wicken Fen as an outdoor laboratory from the 1920s onwards. Godwin's long-running research plots, known as the Godwin Plots, continue at the fen to this day. They are among the world's longest-running ecological experiments. Many hundreds of research papers have been published about this 254-hectare site over more than a century. The swallowtail butterfly, once present at Wicken, declined and was lost in the 1950s despite attempts to reintroduce it — a cautionary data point embedded in the fen's scientific record.

In 1999, marking the centenary of that first two-acre purchase, the National Trust launched the Wicken Fen Vision: a plan to expand the protected area to 56 square kilometres over one hundred years. New acquisitions have since added thousands of acres of former farmland, including Burwell Fen Farm, Tubney Fen, and St Edmunds Fen. The results are measurable. Populations of skylarks, snipe, widgeon and teal have grown. Buzzards, marsh harriers and hen harriers have returned. Bitterns began breeding at the fen in 2009 — the first time since the 1930s. Barn owls and short-eared owls have increased significantly. The Lodes Way, a 9-mile cycling and walking route opened with Sustrans, now connects Wicken to Anglesey Abbey and Bottisham, threading through the expanding landscape. The fen that was once two acres, purchased for £10, is becoming something much larger.