By Megan Lane BBC News Online, in north Kent

The skies over the UK are filling up. To cope with demand, one option is to build a four-runway airport on marshland at the mouth of the Thames - a proposal that has united ecologists and literary fans in opposition. It is hardly surprising that the north Kent marshes have been earmarked as a potential site for a new airport.

A quick glance at the conurbation that is south-east England shows this broad expanse by the Thames to be unusually empty. Above it arcs an enormous sky, deserted except for the occasional light aircraft. On a map it looks like a prime spot for development.

But look closer. The acres of flat marshland that could so easily accommodate dozens of intercontinental jets are teeming with life and steeped in the past.

A view across the marshes at Cliffe

Once the site of a cement works and a World War I munitions factory, the peninsula is once again returning to nature. Indeed, it is regarded as one of Europe's most important wildlife sites (albeit one shadowed by an oil refinery across the river).

Much of the area is now under the auspices of the Royal Society for the Protection of Birds. Grazing sheep and cattle share the wetlands with up to 250,000 breeding and migrating birds, as well as water vole and a rare species of bumble bee.

Although it is thought that building a new airport here is the least likely - and most expensive at a reported �10bn - of the options under consideration, the RSPB is nevertheless gearing up for a fight.

Among its supporters are the musician Jools Holland, who moved to the area several years ago, and Bill Oddie, the bird enthusiast who made his name as one-third of The Goodies.

The reserves are popular with birdwatchers

Michael Ellison, the RSPB warden of the Cliffe Pools reserve, says not only would an airport destroy the natural habitat, planes would risk damage and disruption from colliding with birds - not to mention the dangers of having the oil refinery across the river in the flight path.

"If we can't save this, an area protected by an EU directive and regarded as internationally important, then we may as well give up all hope of winning any future fight."

Echoes of the past

Also under threat is Dickens country. For it is here that Charles Dickens grew up; and here that the novelist set the opening scenes in Great Expectations.

The graveyard that inspired Charles Dickens

In the churchyard of St James in Cooling is a cluster of 18th Century paupers' graves, the "little stone lozenges" over which the hero Pip pondered life and death. Beyond the low stone walls lie the marshes in which the terrified youngster first encountered the escaped convict Magwitch.

In this quiet corner of the Kent countryside, the echoes of the past go back centuries. Today roadways follow in Roman footsteps; indeed, artefacts have been unearthed by archaeologists and local residents alike.

Potter David White, of the village of Cliffe, proudly displays fragments of ancient ceramics alongside his own works, fragments he found while out walking in the nearby RSPB reserve.

A Roman-era pie dish found in the marshlands

Turning over a chunk of blackened pottery in his hands, Mr White explains that it came from a pie dish used by Roman soldiers garrisoned by the Thames some 1,700 years ago.

"Go down just four feet and you come to Roman Britain. If they decide to go ahead with the airport, all this will be lost," he says.

Should the proposal get the green light, Mr White expects there to be fierce opposition, even though it would bring thousands of jobs to an unemployment blackspot.

"We're not yokels or nimbys, we're just people who like our peace and quiet. But not everyone here is against the airport - some say that at least they could sell their houses to the developers."

Undone by nature

Lenny Batchelor believes any plans to build an airport will be bogged down not only in red tape but in the very marshlands being eyed up for development.

Lenny Batchelor for one says it is doomed to fail

Having lived in Cliffe for 85 years and farmed the paddocks that lie between the village and the riverbank, he knows the lie of the land better than most.

"For three months of the year this area is too boggy to even get a four-wheel drive through. Every so often the river spills over its banks - in the 1950s the waters reached my garden, two miles from the river."

With some glee, Mr Batchelor points out another potential hazard: the pockets of peat dotted throughout the marshes.

"Peat tends to explode every so often - I'd like to see what that would do to their concrete runways."