This tranquil bogland is not without its perils

Epping Forest, Essex The deep carpet of moss hides a watery void, and the sparkling sundews are busy trapping insects

The Lodge Road bog is a pool of tranquillity at the centre of the commuter-traffic hum. Both my mobile phone and walkie-talkie radio signals have died, and only a few darting dragonflies break the stillness. Sponging up the sunlight, the bog glistens, a curve of brilliant green amid the deep summer gloom cast by surrounding beeches.

On the outer orbit of London, the survival of this fragile place, the most important habitat of its kind in Essex, seems astounding. Carbon-dating reveals that the first layer of vegetation was laid down here more than 4,000 years ago. Ponded back by a Neolithic trackway, or just some natural lip of gravel, the area was deepened by road building for the various incarnations of nearby Copped Hall since the middle ages.