TO the south of Darlington, the Tees flows a sinuous course. It snakes past Middlesbrough FC's Rockliffe in a broad loop, before doubling back on itself into Hurworth. Then it makes a curious kink at Newbus Grange, before slinking by Neasham in the shape of a nose.

And then it heads south, taking Durham miles deep into Yorkshire. But it doesn't like what it sees, it abruptly changes its mind and flows directly north, towards Dinsdale and Middleton One Row.

As it goes on its schizophrenic course, it creates the finger-thin Sockburn peninsula, a romantically isolated place steeped in history and folklore that had become lost in the overgrowth of time.

However, over the past seven years a band of hardy volunteers has undertaken the enormous task of clearing away decades of neglect and revealing 1,000 or more years of history, and now the Grade II* listed hall and the Grade I listed All Saints church are on the market for in excess of £500,000.

The broad sweep of history on the peninsula begins with the Romans, whose Rykeneild Street ran to the east of Sockburn on the Yorkshire side of the river, not crossing until it reached Middleton One Row.

But there was a wath, or ford, across which a traveller could pick his way to the peninsula where, at some time, an Anglo-Saxon called Socca lived. He had a fortified house, or burg - Socca's burg, or Sockburn.

This, though, was more than any old fortified house.

Because here, "aet Soccabyrig", in AD780, Higbald was consecrated as the Bishop of Lindisfarne.

And here, at a monastery called "Sochasburg", in AD796 bishops Higbald, Ethelbert and Badulf met to consecrate Eanbald as the Archbishop of York.

For such significant events to take place, Sockburn must have been an important religious place.

It certainly feels like an important religious place. It is a peninsula, like Durham.

It has a spring - perhaps of holy water. And its prized possession is a tumbledown Saxon church, full of wondrous carvings by skilled stonemasons mixing Scandinavian mythology with Christian symbolism - perhaps working as a centre of excellence for the whole Northumbria region.

All of which is speculation. For fact, we know that when Aldhun was Bishop of Chester-le-Street between AD990 and AD1018, a chap of Viking descent called Snaculf gave "Socceburg and Grisebi" to St Cuthbert's monks who were settling at Durham and building a cathedral.

About a century later, the monks gave the Sockburn estate to the Conyers family.

Why?

Of course, it was because Sir John Conyers had slain the dragon which, for seven long years, had laid waste to fields for seven miles around, its voracious appetite only satisfied by a bath in cows' milk or the blood of a pretty young maiden.

Brave, brave Sir John managed to slice up the poison-breathing serpent with his falchion, and the Tees, which was in flood, washed away the bits before they could rejoin to form an even more fearsome monster.

Any remaining limbs of dragon Sir John planted beneath the huge Grey Stone, which can still be seen a couple of fields away from the tumbledown church.

What can't be seen are the two grand houses that the Conyers family built on the peninsula, although grassy lumps and bumps and ridges and ramparts betray their footprints.

The first house was a medieval manor; the second was a 16th Century mansion set in parkland. One who saw it described the "great dining-hall window", and there remain four huge blocks of stone carved with the words "SECULOR. . .SOLD.DEO. . .I.MORTALI. . .SECULOR".

These words were taken from the Conyers' motto - "Regi seculor. I'mortali I'visibili soli de honor et gloria I'secular seculor", or "to God the only king immortal, invisible be honour and glory world without end". Once they formed part of an imposing hearth or door lintel, but a century or so ago, they were recovered from the Tees where they'd tumbled once time had had its fill of the Conyers.

Their reign at Sockburn came to an end in 1635 when William Conyers died without a male heir. His daughter, Anne, married Francis Talbot, the Earl of Shrewsbury, and the Talbots sold the estate in 1682. The very last of the Conyers is supposed to have died penniless in the Chester-leStreet workhouse in about 1800.

The new owner was Sir Edward Blackett, whose father had made a large fortune in flax, collieries, shipping and politics on Tyneside.

Sockburn was a minor estate for the Blacketts - their principal residences were Matfen Hall, in Northumberland, and Newby Hall, in North Yorkshire - but they liked the place enough to build a Georgian hall.

This, though, is the third mansion of Sockburn, of which today there is no trace except the lumps and bumps in a field.

It was only short-lived as, in 1834, Sir William Blackett's third son, Henry Collingwood Blackett, built a fourth mansion on the peninsula. This is the mansion that still stands, with his arms above the door and his initials on the drainheads, and rain pouring through the roof. It is not inhabitable.

Around the mansion, Henry built a pleasureground. His formal gardens with trickling water features have just been rediscovered by the volunteers.

In 1838, Henry threw a bridge over the Tees near the wath. It was designed by William Hambley of London, at a cost of £1,200 (about £1m today), and it had powerful pillars built of red sandstone quarried from the riverbed, and its carriageway was carried on Baltic fir timber imported from Lithuania.

Then Henry and his wife, Theophania, turned their attention to the elderly church, where people had worshipped for more than 1,000 years.

That history didn't suit their purpose. What they wanted was a romantic ruin so they could gaze upon it from their stately home and muse, like poets, on the passage of time.

So, in 1838, they pulled the church down. They left standing only its empty windows as an evocative silhouette.

To compensate, they built a new All Saints' church at Girsby, high on the opposite bank of the Tees. They even kitted it out with Sockburn's bells.

Henry died in 1856 aged 47, having been an invalid for some years. His body was carried for burial amid the ruins he had created by his six oldest labourers.

"There was no roof left to echo back the responses to the fine and hopeful burial service, nor any steepled bell to toll the mournful event to the surrounding district, " reported a local paper.

The journalist was deeply critical of Henry's vandalism of the ancient church - "he did injustice to his naturally good taste and mortified deeply the antiquarian spirit" - but was captivated by the scene before him.

"In glorious sunshine, the company stood clustered around the vault, with the solitary yew tree and broad and brightly green park on the one side, and the ruin and hall itself on the other - the river flowing in front, " he wrote. "The whole lacked nothing of a perfect picture which JMW Turner would have loved to render."

Theophania remained. She began enveloping the peninsula in the cloak of privacy that has concealed it until very recently.

When she barred ordinary people from accessing the ruined church, as their ancestors had done for centuries, Darlington Highways Board took her to Durham Assizes. The Board won, and Theophania was ordered to re-open the footpath. Instead, at her own expense, she built a new metal bridge beneath Girsby church. A stone tablet on the Durham side records her name and says this is the Bridle Bridge, built in 1870 and engineered by Henry Dyke.

The Bridle Bridge steered the ordinary person away from Theophania's pleasureground and left her to live undisturbed in her mansion until her death in 1877.

Many country Victorian estates faded when their founders - and their seemingly limitless supply of money - passed away. It happened to Rockliffe down the road in Hurworth, and so Sockburn never recovered from Theophania.

The Blacketts rented it to well-off businessmen until it was sold for £41,000 in 1950 as a property investment to the North England Steamship Company of Stockton. At this point, some pigs seem to have taken up residence in the hall.

In the mid-Fifties, it was bought by Richard and Lucy Gatheral. He had served in both world wars, ending up as a colonel in the Durham Light Infantry, and had then gone into timber importing.

They drove the pigs out, and began restoring it as a family home. Cruelly, injury and illness intervened before they could fulfil their vision, and in 2007, their granddaughter, Laura Geary, devoted great energy and enthusiasm to the enormous task of peeling back the years of decay. With volunteers from all over the country camping on the site, the ornamental garden has slowly reappeared, and the buildings themselves have been made watertight.

Now Sockburn awaits its next chapter...