THORNTON HALL is a place of blocked up windows and secret tunnels. It has a lost history, an avenue of trees that leads nowhere, and a rarely seen ghost.

But it is also a place of open gardens, of beautiful views, of colourful displays, and of afternoon teas – and it is a place that is open on Bank Holiday Monday, raising money for charity, with a plant fair in its courtyard.

Thornton Hall is on the outskirts of Cockerton. It is one of just seven Grade I listed buildings in the borough of Darlington, which means it is in the top one per cent of the most important buildings in the country.

There has probably been a manor house beside the Staindrop Road since time immemorial, although our story really begins around 1550 when Robert Tailbois, of Hurworth, married the heiress of “Thornton of Thornton” and so acquired the Thornton estate.

His son, Ralph, then took over, and in 1569, during the Rising of the North when many leading members of the Durham gentry supported the Catholic rebels, Ralph remained loyal to the Protestant Queen Elizabeth – he was a captain in her armed forces, earning eight shillings a day.

Ralph was rewarded for his loyalty by being given the neighbouring estates of Ulnaby and Carlbury, and with his new-found wealth, Ralph built the southern wing of Thornton Hall – the face that greets visitors to the gardens.

Indeed, it may even be Ralph’s fierce gargoyles – “right ugly nondescript animals”, according to a Vcitorian historian – which stare down on visitors as they approach the front door.

The initials of Ralph and his second wife, Jane Bertram, are to be found carved elegantly into ancient beams at Thornton, and his coat of arms has been moulded in plaster on the ceiling of the Long Gallery – the same coat of arms can be found on the tower of Hurworth church.

Ralph died in 1591, and his son, another Robert, took over. Robert married a daughter of the Bishop of Durham, but not even that could save him – he died in 1606 a prisoner in Durham jail, guilty of an unrecorded misdeamour (probably disloyalty to the monarch). Being a kindly chap, he left £90 in his will to pay for “the dyet of my wife” for the next three years – that means that this Mrs Tailbois was consuming food worth more than £8,500-a-year in today’s values.

The incarcerated Robert left no heir, and so for about a decade Thornton Hall was owned by the Salvin family of Croxdale. In 1620, Henry Bowes, a merchant adventurer who was Sheriff of Newcastle, bought the hall, and it was his son, Sir Francis, who added the northern half in the 1630s.

This substantial extension, including a grand oak staircase, is said to have been necessary to satisfy Sir Francis’ third wife, Margaret Delaval, whose family hailed from the palatial surroundings of Seaton Delaval Hall, in Northumberland.

Sir Francis was loyal to Charles I during the English Civil War. When the king lost, Oliver Cromwell’s Parliamentarians fined Sir Francis £544 on April 28, 1646 – more than £100,000 in today’s values, but he was able to pay it off within a month, and carry on his building work at Thornton.

Such large fines meant nothing to the Bowes family, but paying taxes clearly did. One of the most striking features of Thornton Hall is how many of its grand, mullioned windows have been filled in to avoid being liable to the window tax.

Today, a window tax sounds laughable, but it was a fairly fair measure when it was introduced in 1696. The state knowing the size of an individual’s income was regarded as an appalling intrusion into private affairs, so what better way to judge a person’s wealth than counting the number of windows in their property? It was also an easy tax to administer – whereas an industry of accountants has grown up around income tax collection, all that was needed to work out many windows you had was someone who could see and count.

It was a banded tax: if you had six to nine windows, you paid 2d tax per window per year; 10 to 14, 4d; 15-19, 6d; over 20, one shilling…

Of course, Chancellors of the Exchequer tinkered with the bands in every budget, but the principle was clear: the richest in the biggest houses with the most windows would pay the most tax – unless they bricked up their panes.

By 1718, the revenue from the tax was falling as people tried to pretend they didn’t need so much light in their houses.

Although the tax worked well for people in rural areas who lived in cottages with few windows, in the cities, working-class people lived in huge tenement blocks with vast numbers of windows, so their tax bills bore no relation to their ability to pay.

The window tax also became responsible for people living in dark, unventilated properties – some pernickety window tax collectors even defined larder airholes as windows – and it became regarded as an unhealthy tax, and it was repealed in 1851.

However, many ancient houses, like Thornton Hall, have yet to get round to unblocking their windows.

The last of the Bowes family to live at Thornton was George, who died in 1752, leaving three daughters. One daughter married Lieutenant-Colonel Thomas Thoroton of the Coldstream Guards; another married the Reverend Robert Croft, of Stillington, in North Yorkshire, while the third, Margarett, didn’t marry at all. Their inheritances were rolled into the Thornton and Croft Trust which still owns the hall, and which, over the centuries, has rented the hall to farmers.

Since 1752, therefore, Thornton hasn’t been the home of one of the leading industrialists that so made their mark on a borough like Darlington. As a consequence, it has punched beneath its weight, and its tenants have at times allowed it to flirt with dereliction.

When the current residents, the Manners family, first let the hall in 1947, the formal gardens of the Tailbois family had disappeared as the cows and sheep grazed right up to the back door.

“I just wanted somewhere where the children could play without getting covered in cow muck,” says Sue Manners, who joined her husband, Michael, in the hall 30 years ago. “We got a swing and a slide, and then we made a tennis court, but the bounce was terrible.

“I got my first small greenhouse in 1994, but I didn’t know a thing about gardening.”

The turf of the cows’ fields was dug up, and first of all the Tailbois’ 16th Century garden with its raised beds leading up to a belvedere was rediscovered, and then a large less formal garden, with a wildlife pond, was created.

“It’s a hobby that’s got out of hand,” says Sue. “I just got hooked – you’ve got to have something in life, and it’s just as well I didn’t like posh clothes.

“I just had a blank canvas, with no masterplan, but there’s nothing right and nothing wrong.”

The garden was first opened, to acclaim, in 2005, and now opens a handful of times a year before harvesting becomes the focus of the farm’s efforts. Homemade lunches and afternoon teas are available, and this year there is a fine art bronze sculpture exhibition.

Some visitors come to admire the plants that are Sue’s handiwork; others come to soak up the history.

And everyone wonders at the avenue of limes in the field opposite that leads nowhere. They look at an arch in an outhouse which is said to be the start of a secret tunnel to Walworth Castle more than a mile away (there is another arch in a cellar at the castle where the tunnel is said to come out), and when they hear a strange rustling sound, it could be the silken dress of the White Lady who haunts the upper floors or, more likely, just the wind in the leaves of the “veteran mulberry” tree that has for centuries stood at the entrance to this marvellously historic, but rather hidden, place.

THORNTON HALL, on the B6279 Staindrop Road (DL2 2NB) is open on Monday from 10.30am to 4pm, when there will also be a special plant fair. Admission is £7 per person, and all proceeds go to charity: this year the Great North Air Ambulance, Alzheimer's Research, and Prostrate Cancer. It is also open on June 13, 20, 27 and July 4, 11 and 15.

THE TAILBOIS family, who built the first part of Thornton Hall, are a fascinating footnote in English royal history.

Ivo de Taillebois invaded in 1066 with William the Conqueror, who rewarded him with an estate in Lincolnshire. The family gradually spread north, founding Neasham Abbey in 1272 and becoming lords of the manor of Hurworth.

The Tailbois’ big brush with history came in 1517 when Gilbert Tailbois was declared insane. His wealthy young heir, another Gilbert, was made a ward of King Henry VIII until he came of age.

In 1519, the king appears to have arranged young Gilbert’s marriage to Elizabeth Blount, who just happened to be heavily pregnant with the king’s illegitimate child.

Henry thought he was doing his mistress a favour by finding her a wealthy husband, and Elizabeth did Henry a favour by giving birth to a boy – this proved, to Henry at least, that he could produce male heirs and so it was the fault of his first wife, Catherine of Aragon, that he wasn’t. Catherine, therefore, was divorced.

This made Mrs Tailbois the talk of court, and so there was a little rhyme about her – “Bless ’ee, Bessie Blount” – that was on everyone’s lips for years afterwards.

DARLINGTON’S Grade I listed buildings: All Saints’ Church, Sockburn; St Andrew’s Church, Haughton; St Cuthbert’s Church; St Michael’s Church, Heighington; Butler House and the Rectory, Haughton; Walworth Castle, and Thornton Hall.

THE NORTHERN ECHO is running a photographic competition in conjunction with Thornton Hall. Visitors are being invited to submit pictures taken in the gardens in two categories – flora and fauna, and heritage – by July 4. The prizes will be afternoon tea for two at the hall. For full details of how to enter, go to