What is happening to the stately homes of Britain

It is a great sadness,'' she says. Since 1948 Veronica Tritton had delighted in sharing her Elizabethan house with visitors. It was one of the most beloved in southern England.

Now, an unfamiliar stillness has settled over it. Parham House, near Storrington in West Sussex, has succumbed to the recession.

Similar tales are being told all across Britain. The deathwatch beetle, dry rot, Draconian taxation, and the wrecking ball have all grievously mauled this nation's historic houses over the past century and a quarter. A sluggish economy now threatens them with further ruin.

Parham House, perhaps visited by the Virgin Queen herself in 1593, might have been better appreciated as a national treasure. Restored and furnished with great sensitivity, it is at once unassumingly noble and engagingly domestic - qualities attested to by an airy, picture-hung great hall with its soaring windows, stone fireplace, and paved floor. Lived in, it radiates a warmth and peaceableness.

This season, however, only Parham's gardens have been open to the public. Increased running costs and a sizable decline in visitors forced the house to close. Though numerous such cases have shaken the owners of Britain's historic houses, they are by no means ready to despair. Indeed, many are battling with great vigor and ingenuity to keep their houses open.

Those Elizabethan statesmen, Georgian oligarchs, and Victorian magnates who strewed the British countryside with splendiferous and haughty piles little realized what burdens they were bequeathing their descendants.

Perhaps, as Lord David Cecil has suggested, gentler and more contented spirits would not have felt the urge to create such buildings. But even if many of the builders were indeed fierce, restless, and unscrupulous (as he surmises), they settled on Britain a lustrous heritage. Threats to a historic heritage

In 1950, when for various economic and social reasons historic houses were being demolished at an unparalleled rate all across the country, a government committee under Sir Ernest Gowers reported that the more important ones constituted ''an association of beauty . . . art and . . . nature . . . seldom, if ever . . . equaled in the history of civilization.''

Today, that ''association of beauty'' is facing its severest test since wrecking crews were tearing into it some 30 years ago.

''The tourist boom of the '70s is now sadly behind us,'' observed Lady Mansfield of Scotland's Scone Palace recently. ''The downward trend of the early '80s is already obvious enough to make us tighten our seat belts and take alert and uneasy notice.'' Bluntly, visitors are not pouring into historic houses the way they used to.

In 1972, for instance, 320,000 people trooped around Longleat House, the Marquess of Bath's ancestral home in Wiltshire. In 1981, the year that admissions to historic buildings in England fell by 10 percent, only 150,000 came to see it. Last year, Lord Tavistock's Woburn Abbey in Bedfordshire suffered an 8 percent reduction in visitors.

In Lord Tavistock's opinion, the houses that will be compelled to close in a prolonged recession will be the remoter ones ''on the north coast of Norfolk or in the Highlands of Scotland,'' which necessarily have short seasons.

And if such houses begin to flounder, it is most unlikely that the savior of so much of Britain's art, architecture, and countryside, the National Trust, will hasten to their aid. Entirely reliant on donors, members, and the general public for its existence, it is always short of ready cash. And it already owns some 140 historic houses - which tax its resources more alarmingly each year. The National Trust is often criticised for its ''sad'' and ''mummified'' houses.

When the National Trust does take on a house, it insists that a very substantial endowment accompany the home. Some years ago it rejected Arundel Castle in West Sussex - even though the Duke of Norfolk was prepared to hand it over with (STR)500,000 ($750,000).

''It has never been the policy of the trust to be acquisitive,'' says St. John Gore, a former National Trust historic buildings secretary. ''It has always recognized that the best solution for the country house is the private owner. Its aim is to act as a safety net should the maintenance of a house prove to be beyond the family's means.'' Indeed, the trust hesitates to accept a house where neither an heir nor a tenant can be found to occupy it. A king's ransom for upkeep

For both the trust and private owner, preserving a historic house is a daunting task, one that perhaps is not fully appreciated by visitors.

While rain and industrial pollutants assail a house's exterior, light and dust can play havoc with its contents.

''We're near the world's first, second, and third largest brickworks, which spew out sulfur,'' says Lord Tavistock, ''and sulfur is extremely damaging to virtually anything it touches.'' As a result, Woburn's stonework requires constant re-facing. In 1976, (STR)60,000 had to be spent on the north courtyard alone.

Visitors inflict considerable wear and tear on a house, and few owners can afford to be as philosophical as the eighth Duke of Devonshire - who, when warned of their effect on Chatsworth, replied: ''I dare say they will bring down the floors some day, but I don't see how we can keep them out.'' In 1910, two years after he passed on, Chatsworth was visited by some 80,000 people.

For both the National Trust and the private owner, structural repair bills are to some extent offset by grants from the government's Historic Buildings Councils, set up in the wake of the Gowers Report. But in return for this assistance, owners are required to open their houses to the public - just as they are if they want to escape the exacting Capital Transfer Tax introduced in 1974. But George Howard of Castle Howard in North Yorkshire feels the grants are ''woefully inadequate.''

When not plugging holes in roofs and restoring cracked walls, historic-house owners are tending collections that are often priceless. Woburn's pictures, which include works by Canaletto, Rembrandt, Reynolds, and Gainsborough, keep six highly qualified restorers busy. Five other craftsmen lavish attention on its furniture. With costs mounting and visitors dwindling, many owners face a dilemma: They can either close down or provide additional attractions in the hope of bringing back the crowds.

''If you don't want to put a roller coaster in the back garden, then you can only really sell your house on atmosphere,'' observes Nigel Thomas, private secretary to the chairman of the Historic Buildings Council for England. ''And that seems to have been oversold. People now do actually go for the roller coasters.''

Nobody in Britain has had greater success with ancillary attractions than Lord Montagu of Beaulieu. At the heart of the complex he runs with such flair in Hampshire lies his extraordinarily popular National Motor Museum, with its gallery of record-breaking speedsters.

Lacking Van Dycks and Chippendale in Palace House, his ancestral home, Lord Montagu concluded many years ago that ''what one was selling was a good day out for all the family.''

The motor museum, he says, ''put Beaulieu on the map.'' Of English historic buildings attracting more than 200,000 paying visitors in 1981, Beaulieu ranked seventh, pushing Shakespeare's birthplace at Stratford-on-Avon into eighth place.

''If you're in this business you might as well do it as well as possible,'' advises Lord Montagu, who adds that a title is ''worth about 30,000 to 40,000 visitors a year to a stately home.''

Despairing of making a profit on their houses alone, many owners have acquired additional attractions over the years. In fact, several hundred now have golf courses, nature trails, adventure playgrounds, and, in imitation of Longleat and Woburn, safari parks with assorted wild animals. A ''jungle with living exotic butterflies'' awaits visitors to Compton House in Dorset, and special VIP tours are a specialty of Saltwood Castle in Kent. But by no means do all these attractions make a profit.

Last year over 200 houses staged special events - from a medieval jousting tournament at Belvoir Castle in Leicestershire to an Edwardian fete at Polesden Lacey in Surrey.

If some owners feel a need for more ambitious undertakings, examples are not hard to come by. In 1977 Lord Tavistock staged an open-air concert at Woburn starring pop singer Neil Diamond. ''It was one of the most magical evenings of my life,'' he says. ''Neil is a sweet person and a brilliant performer.'' The crowd of 56,000 was ''beautifully behaved,'' he recalls.

Dispensing hospitality is another means of keeping a historic house open. At Goodwood House in West Sussex, Lord March stands ready to lay on dinner parties, trade promotions, product launches, fashion shows, balls, and wedding receptions. ''If you want to look at the Canalettos - do so!'' exclaims his promotional literature. ''If you want to put up a banner or a film screen, we will take the Canalettos down!''

Norman Hudson, a consultant for the Historic Houses Association, which won the capital transfer tax exemption for owners, maintains that anybody who opens a house to the public is ''actually in a branch of show business.''

But show business is not something that comes easily to most historic-house owners - even though Lord Tavistock's father, the Duke of Bedford, showed what promotional flair could achieve when he opened Woburn in 1954 and proceeded to make it the best-known historic house in Britain.

''He took this business into the 20th century,'' says his son with pride. In fact, the Duke of Bedford had no choice but to publicize Woburn with a passion: He had to pay off (STR)5 million in estate duty incurred on the death of hism father, the 12th duke.

To attract people to what had, in effect, been a long-secluded treasure house , he opened the grounds to a nudist convention; set fire to furniture as a stunt; and invited Marilyn Monroe to spend the weekend and sleep in Queen Victoria's bed. He even appeared on television, singing Noel Coward's ''The Stately Homes of England'' with Lord Montagu.

''His fellow members of the House of Lords thought it was all terribly vulgar and very much not the thing for an English duke to do,'' says Lord Tavistock. The duke was unmoved by such disapproval, declaring to the Sunday Despatch in 1958: ''Fortunately I was never brought up as a gentleman, so I have never had the consequent limitations.'' The destruction abates

Often the refusal to let an ancestral home crumble away stems from a deep sense of inherited responsibility.

Although Chatsworth loses (STR)100,000 a year, the Duke of Devonshire remains at the house as much out of a sense of duty to his tenants and employees as anything else. He and the duchess love Chatsworth. ''It is a terrible place to house-train a puppy,'' confided the latter last year in a witty best seller which revealed literary gifts every bit as luminous as those of her novelist sisters, Nancy and Jessica Mitford.

Regrettably, Britain's affection for country houses has not prevented their widespread demolition - as an exhibition at London's Victoria & Albert Museum revealed in 1974. Entitled ''The Destruction of the Country House, 1875-1975,'' it was estimated that 1,116 - and perhaps as many as 1,500 - were destroyed, partially destroyed, or severely altered during those 100 years in England, Scotland, and Wales. The great majority were simply torn down. Moreover, in the 30 years after World War II, 712 were demolished, gutted, or allowed to fall into ruin.

The book of the exhibition still makes horrifying reading. When Nuthall Temple in Nottinghamshire, a mid-18th-century Palladian jewel, was demolished in 1929, the wrecking crew ''ripped apart an octagonal hall containing the liveliest rococo plasterwork of the century,'' declared John Harris, one of the book's co-authors.

The catastrophe of this ''dreadful series of demolitions,'' as Mr. Harris called them, has been ascribed to the loss of heirs in World War I; the almost penal levels of income tax and estate duty demanded of many owners; the agricultural depression of the late 19th century; and the gradual disappearance of domestic servants.

Many houses, moreover, were grossly ill-treated during World War II when requisitioned by the military for service as hospitals and headquarters buildings.

Some owners demolished houses because they thought them old-fashioned and uncomfortable, but many others did so simply because they lacked the wherewithal to maintain them. ''In the spring of 1944,'' wrote Evelyn Waugh in a 1959 preface to a revised edition of ''Brideshead Revisited,'' ''it was impossible to foresee . . . the present cult of the English country house.''

The destruction of Britain's historic houses, which some say peaked in 1955, did not appreciably abate until about 1969, when government permission was first required to demolish a house of any consequence.

''The tide of demolition has been very, very much slowed down,'' says Marcus Binney, architectural editor of Country Life and chairman of SAVE Britain's Heritage, a group that campaigns on behalf of endangered buildings.

Few think the devastation of the past could occur again. But SAVE believes there may be as many as 140 empty historic houses in Britain - all of them endangered to varying degrees. One, Bank Hall, a splendid Jacobean house in Lancashire, has been empty since 1945. Never offered for sale, it is now tragically decayed and overgrown. Melton Constable Hall in Norfolk, a late 17 th-century house that enjoyed a brief celebrity in the 1971 film ''The Go-Between,'' has been empty for more than a decade.

Many empty houses will, no doubt, be rescued. Indeed, of 56 featured in Tomorrow's Ruins, a 1978 SAVE booklet, two-thirds have found new owners and uses.

Various alternative uses for empty and decaying country houses were suggested in another SAVE booklet, The Country House: To Be Or Not To Be, by Marcus Binney and Kit Martin. Their preferred solution: conversion to houses and apartments. ''If it is done well, it should do zero damage to any significant interior,'' says Binney.

As with everything else, though, such conversions are at the mercy of the economy.

For the owners of Britain's historic houses, the final years of the 20th century seem to promise much uncertainty. That a recession should be visiting hard times on them now when they have won some degree of freedom from injurious taxation seems particularly ironic.

But if the future of Britain's historic houses seems to rest with implacably destructive economic forces, George Howard and Lord Montagu believe that their owners, given sufficient drive and imagination, can avert disaster. ''It really comes down in the end to the individual owner who gets off his backside and does something,'' says Lord Montagu.