IN 1926, Queen Mary, on short notice, insisted on coming to visit Jimmy and Dorothy de Rothschild at Waddesdon.

The date was not convenient -- a Sunday, after a huge Liberal fete was to be held at Waddesdon on Thursday. But no other date would suit the queen. She wanted to come at 3 p.m. for tea. Then on Friday, a message came from the king to ask if he could come along -- for lunch.

Mrs. de Rothschild in her book, "The Rothschilds at Waddesdon Manor," goes on to tell how she coped.

She had asked the queen to plant to tree to mark the event. But now she was told that it would be rude not to ask them both to plant separate trees. This threw her in a dilemma because, as she noted, "suitable trees did not grow on bushes." Her gardener solved the problem -- he dug up a small existing tree so it could be planted again.

Their appearance on the terrace was to be a signal for the fountains to be turned on. "Instead of emitting graceful cascades of glistening drops high into the sky, they produced a sluggish minimum of water accompanied by a series of gurgles and plops of a distressingly suggestive nature.

"For several minutes we all stood solemnly listening to these gurgitations: then the Queen was the first to dissolve in laughter and thus released the pent-up giggles of everyone else present . . . the rest of the visit was conducted in a spirit of hilarity."

Dorothy (Mrs. James) de Rothschild, in her mid 80s, has brought us stories from a distant time and place in the book just published by Vendome Press/Viking Press ($17.50). Kings and queens came to lunch. Bankers collected art -- sometimes on the installment plan. And barons built magnificent manors.

Baron Ferdinand Rothschild built Waddesdon on 3,200 acres near Ayesbury, not far from London, to house what is said to be the greatest non-royal collection of art still intact in England.

Only Mrs. de Rothschild could tell the story so well, not only because she knew the people as well as the palace, but because of her remarkable ability as a writer and her wonderful sense of the ridiculous. It is a rare glimpse of what it was like to be a Rothschild, have all that money and all that taste, and live in England during the drastic changes of the past 100 years. A television program made from this book would rival any of BBC's Edwardian pomp and circumstance scenarios.

Because of intermarriage, her husband had only one great-grandfather, though most people of course have eight. The founder of the art collecting Rothschilds was Mayer Amschel von Rothschild, of Frankfort, Germany. (1744-1812). He was the financial adviser to the Elector of Hesse -- a post he gained because of his "collection of rare coins and his skill as a chess player." Mayer Amschel kept one of his sons in Frankfort, but sent the other four to open banking houses in Austria, England, France and the Kingdom of the Two Sicilies. As Mrs. Rothschild says, "They operated their banks as a single unit."

"In the course of time the progeny of the other four sons intermarried continuously -- in some cases for three suceeding generations. Such intensive inbreeding seems to have sustained a natural aptitude for finance as well as a distinct scientific bent. Common to all was a flair for quality and a love of collecting, whether it was of works of art, books or butterflies."

Mrs. de Rothchild's father-in-law was the youngest son of Mayer Amschel's youngest son. She says she long ago found it simpler to say "cousin" when asked what relation anyone was.

Her own husband, called Jimmy, had tried to escape the family business. "Following a serious concussion he sustained through a fall at Cottenham (he was a great hunter and steeple chaser), he emigrated under an assumed name to Australia, hoping to avoid entering the Pairs branch of the family bank. For 18 months he successfully eluded his family's attempts to find him and earned his living in various ways, starting as a book-maker's runner on the Melbourne race-course and ending as a cattle-hand on a northern ranch. Much to his annoyance . . . his whereabouts were traced by his English cousin Alfred, who prided himself on his world-wide connections.

Later, after working in the bank, Jimmy de Rothschild in 1918 helped raise a Jewish battalion for service, with recruits including Ben-Gurion. Jimmy de Rothschild emigrated to England after meeting and marrying Dorothy Pinto in 1913. She was a 17-year-old bearty. So young, she wrote, that she had just been allowed to stay up to dine with her parents at 7:45. Her education, she writes, had not included boarding school or exams but consisted of speaking French at home and learning "the rudiments of golf, croquet, lawn tennis, bridge, bezique, riding and walzing."

Her narrative is helped greatly by quoting from the unpublished 19th-century "Reminiscences of Baron Ferdinand de Rothschild," who built Waddesdon Manor on the 3,200 acres he bought. At Mrs. de Rothschild's husband's death, Waddesdon and 157 acres around the manor house went to the British National Trust.

She still lives on the large estate, at Eythrope. The pavilion at Eythrope was originally built without bedrooms by the baron's sister, Alice. She had rheumatic fever and was told not to sleep at Eythrope because it was too near the River Thames. So every night, she drove the four miles across the estate to sleep at Waddedon. After Alice died Mr. and Mrs. James Rothschild inherited Waddesdon. They rented Eythrope to Mrs. Somerset Maugham, who build bedrooms and bathrooms.

Waddesdon Manor was started in 1874, when Baron Ferdinand, whose mother was a London Rothschild and father a Frankfort Rothschild, inherited his father's money.

The house was designed by M. Destailleur, a French architect, in the style of the chateaux of the Valois. Most of the paneling came from the French houses torn down during Baron Haussman's reconstruction of Paris.

On the practical side, the baron, in search of decent water, not only piped in Chiltern Hills' water to Waddesdon but also to the village.

The baron, though a Rothschild, didn't always have the money he wanted. Mrs. de Rothschild confides: "I remember my father-in-law's description of Baron Ferdinand impatiently panting to receive the where-withal in order to be able to acquire some particularly longed-for work of art."

In his reminiscences he wrote about his first major purchase, a Sevres Vaisseau-a-Mat, a potpourri vase in the shape of a sailing ship:

"I was unable to pay ready money for this piece of china -- the best I possess -- and blush to confess that I discharged my debt by installments extending over two years. During these two years, I hid the ship in a cabinet afraid to own it lest I should be scolded for my extravagance by my Uncles, of whom I stood in considerable awe."

Later, the baron went on to buy Gainsborough's "The Pink Boy" and Louis XVI's Benneman writing table, Savonnerie carpets and Riesener commodes. He is credited with beginning the interest in French 17th-and 18th-century decoration.

He was, withal, a practical man. Mrs. de Rothschild reports that "all the vast windows have secure inner shutters made of wood. In the daytime these are folded back and only the last panel of any shutter is visible and this is made of beautiful oak.All the other panels are made of the plainest deal (pine), since, by night, when the shutters are closed, they are completely concealed by the curtains. . . ." All the carpeted floors were made of rough planks.

Baron Ferdinand also occupied a very important position in the politics of the day. Mrs. de Rothschild suggests that he was a prime informant of the Prince of Wales, who had been barred by Queen Victoria from any knowledge of state matters. It seems significant that "many people appeared to come to stay at Waddesdon immediately after they had taken part in some notable event. As an instance, Lord Wolseley, on reaching this country after the capture of Khartoum, headed straight for Waddesdon, as did British ambassadors after important international conferences, or war corresondents, hot-foot from some Balkan war."

Once the baron had to entertain the Shah of Persia in the place of the Prince of Wales. The shah was so mad that the prince didn't come he stayed in his room and sulked. But the baron lured him down with the promise of an after-dinner conjurer.

It was quite a logistics problem to schedule convoys to and from the station for the customary 24 guests for a weekend party. One guest told Mrs. de Rothschild that after greeting his guest, the baron asked, "When are you leaving?"

But by far the most extravagant organization was needed for Queen Victoria's visit in November 1888, as the baron explains in his memoirs.

The queen took her lunch in the large dining room, while his guests lunched with the baron in the small dining room.

"The royal appetite is proverbial, and it was not until about half past three that the Queen and her daughters reappeared in the Red Drawing Room. Evidently my cook had done his duty, for, as I was afterwards informed by my butler, Her Majesty partook of every dish and twice of cold beef.

"At last the expectant guests were allowed to sun themselves in the Royal Smile, but their conversational powers were not severely taxed, as Her Majesty was only pleased to address a few stereotyped sentences to those of them with whom she was better acquainted, while those whom I had to present, had to rest satisfied with a gracious smile."

After her Majesty rested after lunch, the baron, kneeling on one knee, gave her a 17th-century ivory fan. His gardener was shyer -- the baron reported that he "would have bolted straight away had I not held him back by the coat tails." Others of the baron's staff were bolder and "copiously dosed with champagne" the Daily Telegraph reporter "to secure their being mentioned in his report. . . ." The baron figured it was all worth it when the guests were assembled on the vestible to say goodbye, and the Queen, alone on the doorstep "curtsied to the company in the most dignified and graceful manner -- a marvelous performance."

Unfortunately, the last visit of the Prince of Wales to Waddedon was not as successful. He slipped on the spiral staircase and broke his kneecap. Mrs. de Rothschild found out many years later that when he was being carried to the station to return to Windsor Castle, "His weight became too much for the carrying chair. It broke, depositing him unceremoniously and most painfully in the middle of the bridge which from time to time, was engulfed by the acrid smoke of trains. . . ."

After the baron's death in 1898, his 51-year-old spinister sister inherited the property. She always walked through the garden carrying a garden tool to whack away at the weeds. Mrs. de Rothschild credits her with taking care of the collection -- better than the baron who allowed the sun to shine in and puffed his cigars all over the house.

In Miss Alice's day "smoking was most rigorously restricted to the Smoking Room and the continual adjustment of blinds which she enforced prevented all harmful rays of the sun from falling on textiles, marquetry and drawings. She laid down the most stringent rules about who should be allowed to touch china. No female hand was allowed to dust the decorative Sevres vases in the various sitting-rooms; this was the responsibility of one particularly trusted man only."

The Sevres and Dresden china used in the dining room was washed by the housekeeper and the still-room maid in accordance with Miss Alice's standing order: "When touching china always use two hands and maintain complete silence."

Miss Alice's farewell appearance (she died in 1922, but the war prevented her from entertaining before then) was the 1913 dinner she gave for the officers of the Buckinghamshire Yeomanry. "To celebrate the cessation of a running battle . . . over the Yeomanry's temerity in riding over growing crops when on maneuvers in the park at Waddesdon . . . it took the combined efforts of two Field Marshals, the Duke of Connaught and Lord Kitchener to settle the terms of peace.

During World War II, the house was turned over to 100 under 5-year-old children as a refuge from the bombs of London. Jimmy and Dorothy de Rothschild lived in the Bachelors' Wing and shared the kitchen with the children. Mrs. de Rothschild, while having chicken pox, no doubt caught from the children, organized a vast sewing bee to aid the army.

After the captains and the kings departed, the de Rothschilds found Waddesdon was in less than princely condition. They had hung the best pictures in the grey drawing room because "the danger of Hitler's bombs falling on Waddesdon was less than the known peril ofWaddesdon damp."

But still a tap was left running and a priceless desk almost ruined. And the red drawing room had been "especially vulnerable to sticky fingers; its walls had also been a tempting background for coloured chalk." And the sunlight, escaping from Miss Alice's rules had "rotted its lovely panels into rags." Still money can buy most things, and an 81-year-old weaver, called out of retirement, reproduced the wall covering.

Mrs. de Rothschild has trouble replacing the furniture exactly as it had been until she realized she could match up furniture feet with the dents in the carpet.

They decided to give the house to the National Trust, but James de Rothschild died in 1957 before Eythrope was ready to be reoccuppied. "If it be true," writes Mrs. de Rothscild, "that the best way of keep grief under control is to be forced to be very busy, the Estate Duty Officer of the Inland Revenue must indeed be the widow's best friend." She had to go through all the myrids of treasures and make an inventory, because according to the British law, no taxes were payable unless the objects were sold.

It was particularly difficult in the garden, she wrote, to decide "whether a large nude marble lady peering from her leafy bower was indeed "pomona-18th century . . . . I learnt the hard way it all depended on what produce she happened to be carrying. A similar state of indecision siezed me when confronted by large muscular stone gentlemen. I took it that if they were clamping rather agitated females they were probably the Rape of the Sabines . . ."

With the National Trust, Mrs. de Rothschild took on the problem of publishing a comprehensive catalouge, planned to go 17 volumes, of which 12 have been completed. She asked Sir Anthony Blunt, the art expert, to over see the series. Blunt was recently Surveyor of the Queens's pictures and director of the Courtauld Institute. (He has recently confessed publically to being a Russian spy and was stripped of his knighthood).Mrs. de Rothschild herself took upon the writing of this book in her 80s because, as she said, "I have probably learnt rather more than most about the people who created Waddesdon, who lived in it and transformed it . . . into what it has now become."

She quotes the builder of Waddesdon, Baron Ferndinand, as saying that in a democracy, people have taken the place of prelate and prince as patrons of the arts, and "new centres of attraction" such as Waddesdon are now open to everyone (on visiting days during prescribed hours, of course).

Baron Ferdinand was proud of his work but feared for its future since he had no children. He wrote: "May the day yet be distant when weeds will spread over the garden, the terraces crumble into dust, the pictures and cabinets cross the channel or the Atlantic, and the melancholy cry of the night-jar sound from the deserted towers."

He needn't have worried. The principal treasure of Waddesdon, Dorothy de Rothschild, is still in charge, checking the carpet for fading, and admonishing the maides during the washing of the Sevres. CAPTION: Illustration, no caption, from "The Rothschilds at Waddesdon Manor"; Pictures 1 and 2, Ferdinand de Rothschild and Mrs. James de Rothschild: "A rare glimpse of what it was like to be a Rothschild." By Bern Schwartz, Copyright (c) 1978; Picture 3, The dining room at Waddesdon Manor. From "The Rothschilds at Waddesdon Manor"