THE BBC SCRIPT for the series on the life of Lady Astor called for the landscape to be tinder dry.

But at 9 a.m. of that late May day at Redlands, home of Robert and Bessie Carter at Carter's Bridge, Va., the rain was churning the Albermarle clay into mud. The huge tracks that carry props, costumes, lighting equipment, generators, a beauty parlor, caterers, actors and extras were stuck in the mud, unable to get up the hill into the field that was to be their campground for the next five days.

The rain finally stopped, crushed stone was ordered from a nearby quarry to give the trucks some traction, and a tractor pulled the hopeless cases into place in the field.

The tedious process of filming began, and as the day wore on and the sun came out the red clay dried on the legs of the Dalmatians who ran along behind the carriage, on the cables that ran from the generator to the filming site, and the espadrilles and tennis shoes of the workers.

By late morning Lisa Harrow, who plays Nancy Langhorne Astor, and the supporting cast were stepping gingerly across the lawn, holding their 1890's costumes out of the mud.

Despite the mud, it's easy to see why the BBC picked Redlands to evoke Virginia in the 1890's, standing in for "Mirador," the childhood home of Lady Astor, nee Nancy Langhorne.(The eight-part series is scheduled to be aired in the United States in 1982.)

Redlands sits on the crest of a hill looking south over the gentle rise of the foothills of the Blue Ridge.

Two-hundred-year old oaks, limbs so long and heavy they must be propped up, give shade to the lawn. The driveway, outlined by the wild rose bushes that hug its fenceline, winds up the hill from the Hardware River. Grazing cattle dot the pastures of the rolling countryside and an occassional house or barn can be seen silhouetted against the hazy backdrop of the mountains.

These actors strutting around in their period costumes seem more in keeping with this setting than the spectators who have come to watch in wrap-around skirts, blue jeans and T-shirts.

The 2 1/2-story house was built between 1798 and 1808 by Robert Carter, great-grandson of "King" Carter. The house is a glorious expression of architecture evolving out of a Georgian mold into the freer, more imaginative Federal period.

If the eye can remove the extended front porch and the dormers in the roof, 20-th century additions, the exterior of the house from its main approach on the south is classical Georgian.

A graceful two-story bow in the north wall of the rear gives away the secret of the innovative and delightful interior floor plan.

When you walk into the front hall at Redlands, instead of finding the typical Georgian plan of a central hall with two main rooms on either side, you see the elliptical parlor. The formal room with a dramatic 16-foot ceiling, a floor-to-ceiling French window and intricately-carved decorative trim nevertheless manages to be welcoming.

Portraits of Carter forebears hand from the elaborate plaster moulding, the furniture arrangement around the fireplace mimics the room's shape, and at night the cheerful glow of candles in scones still gives light.

The plaster cornices and moulding, and the carved wooden decoration of the mantel, in this room and throughout the house, reflect the influence of the Robert Adam pattern books with their motifs of wreaths, swags, egg and dart, etc. Among these classical motifs the tobacco leaf has been inserted -- a reminder of the fortune that built the house.

On the second floor the master bedroom mirrors the shape of the parlor below. The interior bow, which was originally used as a bed alcove, was made into a bathroom when plumbing was added in 1910.

The other four bedrooms on the second floor and the guest room of the first floor all contain several beds. One room upstairs has two double beds, a single cot and a crib, and is not crowded. The beds have hand-quilted or crocheted covers. The four-poster in the guest room is covered with a 19th-century crewelwork bedspread. Bessie Carter's mother transposed the crewelwork onto new linen backing when the old backing disintegrated -- a project that took 30 years.

Each major room in the house has its own fireplace. The rooms are connected by interior walkways and doors. Only the upstairs and downstairs halls and the small enclosed staircase were unheated, causing the women of earlier times to throw cloaks over their shoulders when they crossed the hall climed the stairs.

Although it is known that Martin Thacker was the builder, no record of house plans exists, and the architect of Redlands is unknown.This lack of documentation led two University of Virginia architectural students, Drucilla G. Haley and Ed Polk Douglas, to write theses on possible sources of its design.

The carter's oldest son, Robert Hill, did research on family history for a term paper at Williams College. This writer has benefitted from the work of all three students.

Many of the architectural features of the house, notably the insignificance of the staircase, the elliptical parlour and its French window, and the bed alcoves have caused speculation that Thomas Jefferson had a hand in its design. Jefferson, almost as important an early architect as president, politician and patriot, was a friend of Robert Carter's father Edward Carter. Jefferson drew designs for many of his friends' houses, as well as his own Monticello and Poplar Forest and the University of Virginia.

Redlands was a plantation product. The red clay gave the bricks a splendid deep red hue. All the timber used in the house came off the property. The plaster was made on the place by grinding oyster shells brought up the James River by barge to nearby Scottsville.

Much of the furniture arrived by barge as well. The huge glass-front bookcase in the upstairs hall was none the worse for the dunking it received when it fell off the barge and had to be raised from the river bottom.

Several pieces of furniture in the front hall and the parlour came to Redlands from Monticello when , after Jefferson's death, his property and possessions were sold at auction to satisfy his English creditors. Two sconces on either side of the mirror in the hall were bought by Jefferson at a flea market in Paris.

All of the rooms at Redlands are filled with family memorabilia -- tangible evidence that the house has stayed in the loving hands of the Carter family for six generations. Pictures of the children of this generation are placed side by side with musty photographs of no-longer familiar faces on dresser tops, mantels and walls: Photographs of a woman on horseback astride a side saddle in an impossible costume; another of a young man and a woman with a banjo seated on the front steps, the young man obviously courting, and not so obviously giving a bango lesson.

While the house has gained from one family's occupancy, the Carters, on the other hand, have had to make many sacrifices to maintain Redlands. Careers have been sublimated, and studies given up to keep the house in the family. Carter women especially have worked hard for the house.

The first woman to inherit this role was Mary Eliza, wife of Robert Carter, who, after his death at 32 in 1810, was left to bring up five children, finish the interior detailing of their newly-constructed house and manage a 3,000-acre tobacco plantation.

Tobacco requires many workers, and the 150 slaves that worked the crop had to be housed, clothed and fed.

That most of these needs were taken care of on the place is indicated in a letter Mary Eliza wrote in January of 1823. "Tell Betsy I am obliged to her for her offering of shopping but my wants are few, and that I have supplied myself from Charlottesville and Milton, two months ago for the winter."

Grapes were planted, and did so well that in the 1890's cuttings from the Redlands vineyards were sent to France to replace a decimated crop.

The fortunes of tobacco as a cash crop waxed and then waned during the first half of the 19th century. In the 1850's the price rose and it was again a sought-after crop. The prosperity this brought to Redlands came to an abrupt end with the Civil War.

Mary Eliza's son, Robert Hill, had married Margaret Smith of Baltimore in 1834. When her father, Gen. Samuel Smith, died a few years later, much of the furniture from the family's beautiful home, Montebello, ended up at Redlands.

General Smith had also been in the import trade, and Redlands' dining room today is filled with Canton china from this source. A recent family project has been to needlepoint seat covers for the dining room chairs in blue and white designs taken from the china.

Because of this Baltimore connection, Redlands during the Civil War became a mecca for Marylanders who fought on the Confederate side. After the war when they were considered traitors and could not go home, soldiers by the hundreds bivouacked on the lawns and in the fields until laws were relaxed and they could at last return to Maryland.

The war had already bankrupted the economy, and the family's final act of generosity to the Maryland soldiers meant that what little there was to go around for the family was spred even thinner.

In the grim years after the war, two of Margaret and Robert Hill's daughters went into teaching to make a living, and their brother, Robert, was forced to give up his studies.

Eventually, these two daughters, Miss Sally and Miss Polly Carter, ventured north to Baltimore to found a school for young ladies in the hopes that it would help them pay the taxes on Redlands. They started St. Timothy's School, relying heavily on their Smith cousins to help them get it going.

The Misses Carter were hard-working, determined and successful. St. Timothy's is a thriving boarding school about to celebrate its centennial next year.Even in its early years before it became profit making, it provided Redlands with a cornered market for its produce. In the summer when the headmistress returned to Redlands they often brought schoolgirl visitors.

Robert Carter remembers his great aunts and the way they lived in the 1920's after their financial success had restored the good life to Redlands.

A summer day began before breakfast when servants, guests and family all knelt with their elbows on chairs in front of them while prayers were read. a

"At precisely 9 a.m.," says Carter, "The blinds were drawn against the heat. That kept it cool and dark inside -- those old ladies wore ankle-length black linen dresses with high choke collars. The walls of the house are 34 inches thick, which helps to keep it cool, too."

After breakfast, Aunt Sally would take the big key that hung around her waist and open the supply room in the basement. From large barrels she would dole out the flour, sugar and meal needed for the day. Tea came from a toolbox-sized chest.

That done she would mount her horse and tour the farm, talking to the manager and inspecting whatever work was in progress. She rode out on sidesaddle, dressed in a long white skirt, black boots and a black hat.

"Dinner was one of my horrors as a child," reminisces Carter. "It began at 1:30 and lasted at least two hours. Those old ladies and gents would talk and talk and talk. I wish now I had been listening . . . I was bored to tears then."

Dinner would be followed by a nap in the heat of the day. After that the Misses Carter would work at their desks in the study. Carter remembers the mail pouch coming up from Carter's Bridge every morning filled with newspapers from all over the world, and letters sometimes addressed simply "Redlands, Va. U.S.A."

Around 5 p.m. tea would be served on one of the porches or in the rose garden. "It was an elaborate ritual," says Carter, "With linen tablecloths and polished silver. I remember a big tea urn with a spigot and the cinnamon toast that we got as children."

After tea, the older people would take a stroll, making a circuit around the lawns, to work up an appetite for a cold supper at 8:30 p.m.

Reading outloud followed supper.

A Cuisinart and the tireless energy of the Carters and their caretaker's family are all that's left of the staff; but Redlands is still the hospitable center of family life. Thanksgiving is about the only time that the first floor dining room is used for eating, because all the dishes must come up on the original dumb waiter from the kitchen-dining room in the basement.

Two Carter sons, Andrew and Jack, are in college and medical school, and their friends often rent the outbuildings, including an old slave cabin.

Redlands is also a natural gathering place for University of Virginia parties. On Easter weekend the entire freshman class of the medical school and their professors and dates celebrated with a pig roast that started with the spitting and cooking of a 190-pound pig Friday night, and continued on into the wee hours of Sunday morning.

The pig, by the way, failed to feed all those people, so they had to make an emergency trip to Charlottesville for fried chicken.

For Redland's owners, there were larger problems.

A small plumbing leak turned into a major problem when they discovered that the plumbing system, added early in this century, was encased in concrete. A loose plank in the front steps revealed the need to replace the substructure of the porch. Ordering swags for a window that is 12-feet high is expensive. Two hundred year old trees on the hilltop all need lightning rods. The list goes on and on and it begins to seem that the house owns the family.

But every Virginian and all others who love old houses would agree it is worth it.