NEW YORK (NYT NEWS SERVICE ).- In 1983, a wealthy American wandered into the Royal Shakespeare Company in Stratford-upon-Avon in England. He saw a scale model of a new theater that the company hoped to build, if only it had the money. The American said he would underwrite the project, but he wanted to remain anonymous.

Three years later, Queen Elizabeth II presided at the opening of the new Swan Theater. The American, Frederick R. Koch, who had built the theater for $2.8 million, stood by her side. But she respected his wish for privacy: She thanked “our generous benefactor” — but did not name him.

Koch (pronounced coke) kept a low profile for most of his life. When the news media mentioned him at all, it was usually in passing in reports about his three hard-charging billionaire younger brothers: Charles and David, who ran Koch Industries, the industrial behemoth founded by their father, and bankrolled libertarian causes; and William, David’s twin, an eclectic entrepreneur, collector and yachtsman who won the 1992 America’s Cup. (David died in August at 79.)

Frederick, who bore the aspect of an Edwardian gentleman, had little in common with his brothers. He devoted himself not to oil, the bedrock of Koch Industries, or to politics, but to the arts and historic preservation.

Koch died Wednesday at his home in Manhattan, where he had lived, as he preferred, in relative anonymity. He was 86. John Olsen, his friend and longtime assistant, said the cause was heart failure.

As an adult, Frederick, known as Freddie, rarely saw his brothers, except in court. In the 1980s and ’90s, the four were embroiled in what Fortune magazine called “perhaps the nastiest family feud in American business history,” with Charles and David, two of the richest people in the world, allied against William and Frederick.

While Frederick did not share the family’s corporate ethos, he did share, to a lesser degree, its immense wealth. This allowed him to pursue his own interests. A philanthropist and patron of the arts, he amassed extensive collections of literary and musical manuscripts, rare books, photographs and fine and decorative arts. His prized possessions included Marie Antoinette’s canopied bed.

He also collected manor houses in Europe and the United States. The crown jewel was a 150-room castle in Austria once owned by Archduke Franz Ferdinand, whose assassination in 1914 touched off World War I. The archduke used the castle, known as Blühnbach, as a hunting lodge; Koch used it for decades as his summer retreat. It provided easy access to the Salzburg Festival, which he attended every year.

Fred’s spurning of the family business helped fuel the disappointment that Fred Chase Koch, a self-made man and rugged individualist, felt toward his oldest son.

“Father wanted to make all his boys into men, and Freddie couldn’t relate to that regime,” Charles Koch told the now-defunct Fame magazine in 1989.

William Koch, known as Bill, said in an interview for this obituary: “When Freddie was born, he was delicate, he liked the arts, he was a singer and loved poetry. He didn’t want to play baseball.”

And when their father sent the boys to ranches to toughen them up, he rebelled. “Instead of baling hay,” Bill said, “Freddie would hide in the hayloft.”

Bill Koch said that years later, their father discovered that $700 in traveler’s checks were missing and believed that Frederick, who was visiting his parents at the time, had stolen them. Frederick later told Bill that he had not. In any case, their father was furious and, after a lifetime of frustration with his namesake, considered this to have been the last straw.

“He threw Freddie out of the house and cut him out of his will,” Bill said. Through a trust, however, his father, who died in 1967, left Frederick 14% of the company’s stock.

That inevitably tied his fate to that of the conglomerate, which today, according to Forbes, is the second-largest privately held company in the country, with annual revenues of $110 billion. The Kochs are the nation’s third-richest family, worth $125 billion.

By 1980, the brothers, always competitive with one another, were engaged in open warfare over the fate of the company. Much of it was driven by Bill, who enlisted the support of Frederick and a half-dozen other shareholders who wanted to take the company public so that they could convert their stock to cash. Charles saw their moves as a takeover attempt, and the board fired Bill, leading to a lawsuit and 18 years of legal skirmishing.

In 1983, Koch Industries — essentially Charles and David — settled with Bill, Frederick and the other dissident shareholders for $1.1 billion, with $470 million going to Bill and $330 million to Frederick.

But as Fame magazine put it, “all the money in the world hasn’t been enough to keep the family from falling apart.”

Bill and Frederick said they had been cheated in the settlement and went back to court. In a tangential action, they sued the directors of a family foundation, which included their mother, Mary Koch. In response, Bill said, their mother, who died in 1990, excluded him and Frederick from her will.

The fight ended in 1998, when a federal jury in Topeka, Kansas, ruled that Bill and Frederick were owed nothing more. Bill and Frederick eventually reconciled with David, but not with Charles.

Bill and Charles Koch are Frederick’s only immediate survivors. His entire estate, Olsen said, including his investments, real estate and art collection, will be used to establish a foundation to promote the study of literature, history and the arts.

Frederick Robinson Koch was born in Wichita, Kansas, on Aug. 26, 1933. While his father was emotionally distant, his mother, Mary Clementine (Robinson) Koch, was a sophisticated student of the arts and nurtured a similar passion in Frederick.

He left the family home in Kansas in his teens for the Hackley School in Tarrytown, New York, where he was valedictorian in 1951. He studied humanities at Harvard, graduating in 1955. (His father and three brothers all studied engineering at the Massachusetts Institute of Technology.)

After college, Frederick enlisted in the Navy Reserve, then enrolled at the Yale School of Drama, where he studied playwriting and specialized in Shakespeare. He received his master’s degree in fine arts in 1961.

He considered becoming a playwright or drama critic but pursued neither. Instead, with the rigor of a scholar, he set about assembling important collections of literary and musical works as well as real estate.

“When he saw things he loved, he got them if they could be gotten,” Charles T. Young, an architect who helped restore many of the properties, said in an interview.

During the 1980s, Koch bought two apartments and a half-dozen manor houses. He conducted extensive research on these historic residences and allowed the renovations to be guided by each home’s history, setting and aesthetics.

Among them were Sutton Place, a 72-room Tudor mansion and estate in Surrey, England, built in the 1500s; and, on the French Riviera, the palatial Villa Torre Clementina, whose rounded medieval stone towers overlook the Mediterranean.

One of Koch’s favorites was Elm Court, a Gothic Revival mansion near Pittsburgh. The home’s dozens of gables, stone chimneys and pinnacles suggest a small English village.

In Manhattan, he owned two homes. One was a white marble French Regency-style mansion on East 80th Street, where he died. It was commissioned in the early 1900s by F.W. Woolworth for one of his daughters. Ornate paneling from the Palace of Versailles lines the walls.

The other was a one-bedroom apartment on Fifth Avenue, where he lived most of the time and felt most at home.

His real estate holdings at death consisted of the two homes in Manhattan, the mansion near Pittsburgh and the castle in Austria.

Despite Koch’s lavish spending on such grandeur, friends and family say he was notoriously frugal. He took public transportation in New York and flew commercially. He reprimanded house guests for not turning off the lights and quibbled over the excessive use of postage stamps. When going to the movies, he made sure to use the senior discount.

One friend recalled, with affection, that about 10 years ago, Koch spotted a nickel embedded in the asphalt on Fifth Avenue. He borrowed a pen from the friend to try to dig the coin out as cars and buses swerved to avoid him, honking their horns. He stopped only when the pen broke.

The friend later admonished him, saying he could have been killed and that such a scene would have made for an embarrassing obituary.

Koch laughed. Imagining the headline, he said: “Ah! The Fatal Nickel.”

But otherwise he was unsparing. He made numerous anonymous bequests to independent theaters in New York and London. He served on the boards of the Metropolitan Opera, the Spoleto Festival USA in Charleston, South Carolina, and the Film Society of Lincoln Center.

Over the years, his staff cataloged his purchase of more than 50,000 items, many from the elite auction houses in New York and Europe. Thousands of pieces of art and furniture went to his manor houses.

He made gifts to the Morgan Library and Museum, the Frick Collection and the Carnegie Museum of Art in Pittsburgh. He donated more than 400 items to the Harvard Theater Collection, including manuscripts by Tennessee Williams and George Bernard Shaw and a voluminous collection of photographs.

His most substantial gift was to the Beinecke Rare Book and Manuscript Library at Yale, to which he donated an exceptional collection of musical and literary manuscripts. His core collection held more than 2,000 items, including scores by Debussy, Wagner and Verdi.

“These working scores are really important because they show how something evolved from its first appearance through subsequent productions,” Timothy Young, curator of modern books and manuscripts at the Beinecke, said in an interview.

Koch’s literary donations to the Beinecke included Noël Coward’s diaries, page proofs of parts of Proust’s “Remembrance of Things Past” and the corrected typescript of Henry Miller’s “Tropic of Cancer.” A separate donation was of 50,000 photographs, most of them of celebrities, taken by Jerome Zerbe, the photographer of mid-20th century cafe society.

The library often produced performances based on material from Koch’s archives.

“He was happy to attend,” Young said, “though he would prefer to sit in the back of the room and usually left before the performance was finished, hoping to retain his anonymity.”

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