Within the collection of villages that makes up London, the capital conceals domains known, perhaps, only to those who live nearby and visiting schoolchildren.
These are the inner-city wildlife parks, nature reserves and wetland sites, some little bigger than an average back garden, others covering an acre or so and managed so expertly you might think you were strolling along a country path bounded by streams and hedgerows bright with poppies.
The London Wildlife Trust manages 60 of these projects in the capital. Often tucked away unpromisingly behind gasworks, or on the verges of the underground, their unique selling point is that they are secret and beautiful. Adults and children can enjoy the sounds and smells of the countryside, unfazed by the redundant tip over the road or the view of the Post Office Tower a mile or so away.
Even more than her much-loved parks and public greens, these are the lungs of London. It is an inner-city world of willows, meadows, ponds full of darting water-creatures, and half-hidden marshy areas where wildfowl rear their young undisturbed.
The six-acre Gunnersbury Triangle site, one of the first of the Wildlife Trust's projects, was saved from development in the 1980s. It is set between three underground railway tracks (hence Triangle) hard by Chiswick Park tube station.
In the spring, education manager Ian Holt's diary is crammed with school visits. Ian has devised ways of encouraging children to listen, sense and smell as well as see the natural world around them. They close their eyes and use their fingers to feel the different textures of bark, moss and ferns. He provides pads to brush gently over leaves and flower-stems before sniffing the "magic potions" which mark each species one from the other.
From April, holly blue, peacock and brimstone butterflies abound. Following the illustrated guide, you wind among wild cherry and rowan, under archways of hazel branches to a pond where damsel-flies dance in early summer. A sparrow-hawk nests in a silver birch, a jay comes visiting, bees and wood-mice also live here.
There are open glades for picnics and, in autumn, blackberries to gather. The aim here is to manage the woodland as a natural piece of countryside in town, and if, from time to time, you glimpse a tube train, you hardly notice it, beyond the trees.
Gunnersbury Triangle, Bollo Lane, London W4, 5LW. Tel: 0181 747 3881
* Camley Street Natural Park is one of the oldest London Wildlife Trust projects, saved from becoming a coach park by vociferous residents. To reach it you pass between London termini and the skeletons of three redundant gasometers.
Ignore them, enter through a pair of handsome Victorian gates and you're in a hummocky meadow framed by ash and spindle trees. Along a path bordered by campion and marsh-marigold a coot patters awkwardly on enormous feet; beyond, a solitary figure fishes in the canal.
Free to all, groups from local schools come here regularly to study environment-based projects. "You won't find the rare and the wonderful," explains project manager Andy Littlewood. "But there are wrens, missel-thrushes, herons, kingfishers and emperor dragonflies - creatures unusual around King's Cross. The park is a corridor between Regent's Canal and London's outer suburbs ... a convenient motel for birds to rest, feed and even breed on their way out of the city."
Youngsters hunt for sticklebacks, observe the stunning patterns on butterfly wings, climb into a tiny hazel wood and notice how the age-old craft of coppicing restores nature's balance by producing new shoots which attract insects and provide meals for birds.
"The natural world should be part of everyone's life," adds Andy. "And Camley Street is an example of what can be done with derelict land on anybody's doorstep."
Camley Street Natural Park, London NWL 0PW. Tel: 0171 8332311
* As you pass down a street of modest Peckham villas, you wonder if you've missed the way. Suddenly, you turn into a path bordered with cottage flowers: pink and purple valerian, dog roses and sun-gold Californian poppies, and reach the Centre for Wildlife Gardening.
"We're the only centre of our kind in London," explains manager Helen Firminger. "We help local people plan and construct their own wildlife gardens, but we're a communal project, run by volunteers, too. We focus on urban gardens and very small spaces."
Although the whole area takes up little more than an acre, Helen, who trained at art school, has planned a garden with a surprise at every corner by clever juxtaposition of colour shape and texture.
There is a patch of meadow flowers, a herb garden - fragrant with mint, lavender, lovage and aromatic artemisia - an island for birds on a pond fringed with yellow irises, crab-apple, and a bare-branched tree hung with bird-feeders, actually a piece of sculpture made from old piping - all affordable and simple to set up.
The chalet-style visitor's centre is designed to benefit from summer shade and winter sun. It is insulated with recycled newspaper and decorated with organic paint. Inside, courses are offered in garden planning and and how to introduce pond life such as frogs and newts into gardens.
The Centre attracts 15,000 visitors a year. Entrance is free, but donations to this registered charity are very welcome.
Centre for Wildlife Gardening, 28 Marsden Road, London SE15 4EE . Tel: 0171 252 9186.The London Wildlife Trust is based at Harling House, 47-51 Great Suffolk Street, London SE1 0BS. Tel: 0171 261 0447. New free events, sites guides and teaching packs have just been produced