Derby is the spookiest city in Britain, according to a recent survey of ghosts and poltergeists in cities across the country. But the Peak District of Derbyshire also has more than its fair share of strange phenomena. Mysterious flickering lights have been seen dancing over crags, peatbogs, heather and wooded valleys; tiny, ghostly flames a few inches high are said to dance around like a lantern moving in zigzag lines.

These lights are known as the will-o’-the-wisp or Jack-o’-lantern and are usually seen in bogs, marshy ground and graveyards. The Longendale Valley and Bleaklow in the Peak District both have a long history of the strange lights, and legends say that these were fairies, witches or possibly the ghostly torches of Roman soldiers. Tales also told of travellers led into treacherous bogs, which is why they used to be called ignis fatuus, the foolish light. But in Jane Eyre, a will-o’-the-wisp guides Jane to safety when she is lost on the moor: “Far in among the marshes and the ridges, a light sprang up. This light was my forlorn hope: I must gain it.”

In The Song of Hiawatha Henry Wadsworth Longfellow had an idea of what caused the phenomenon. As Hiawatha made his way through the swamp to slay the magician Megissogwon, the dark waters were: “Rank with flags and leaves of lilies, Stagnant, lifeless, dreary, dismal, Lighted by the shimmering moonlight, And by will-o’-the-wisps illumined, Fires by ghosts of dead men kindled.”

The phenomenon is thought to be caused by gases given off from rotten animal and vegetable matter. These marshy gases such as methane may be ignited by another gas, diphosphane, creating the glowing, flickering light.