Stanley J. Seeger, a reclusive, idiosyncratic art collector who disposed of Picassos, Beckmanns and Bacons nearly as fast as he bought them, and who for several years in the 1980s owned Sutton Place, one of Britain’s grandest Tudor estates, died in Whitby, North Yorkshire, on June 24. He was 81.

The cause was an aortic aneurysm, said his companion, Christopher Cone. Mr. Seeger, a Milwaukee native and heir to a family timber and oil fortune, lived most of his adult life in Britain, where he pursued his passion for modern art and expensive houses exuberantly but anonymously. When The Financial Times ran a profile of him in 2010, it claimed that the photograph of him that accompanied the article was the first to be published in his lifetime.

In the meantime, he indulged his highly developed taste for Picasso, modern British artists like Ben Nicholson, historic cookbooks and the illustrator E. H. Shepard, best known for the Winnie-the-Pooh books.

He came to public notice intermittently, and always surrounded by question marks, whenever he decided to auction off a collection that had, as he once put it, “fulfilled itself.” In 1993, when the art market looked very iffy, he sold 88 Picassos through Sotheby’s in New York, spanning the artist’s entire career, from 1899 to 1972. All lots sold, for a total of $32 million.

In 2001, a collection that included works by Braque, Miró, Schiele and other moderns sold for $54 million, with Bacon’s 1979 triptych “Studies of the Human Body” fetching $8.5 million, then a record price for the artist.

“He was absolutely a pure collector,” said David Nash, who handled the Picasso sale and now, with his wife, Lucy Mitchell-Innes, runs the Mitchell-Innes & Nash gallery in Manhattan. “He was not interested in the investment side of things. When he felt that one collection was complete he’d get rid of it and start on another.”

In 1980, Mr. Seeger found himself in the spotlight when he bought Sutton Place, a red-brick manor house built in the 1520s, from the estate of J. Paul Getty for $17 million. With 14 bedrooms, large banquet halls, a 100-foot-long library and more than 700 acres of grounds, it is one of the grandest of English country houses. Its original owner, Sir Richard Weston, entertained Henry VIII in its halls in 1533.

Mr. Seeger embarked on a grand redecoration that raised eyebrows, and a few hackles, in Britain. He modernized the décor and installed much of his art collection in the house, hanging the Bacon triptych of contorted nudes in the great hall. He hired the eminent landscape architect Geoffrey Jellicoe to reconfigure the gardens. A wall by Ben Nicholson was unveiled by the Prince and Princess of Wales.

“I hear rumors of cascades,” the Queen Mother told the royal biographer Hugo Vickers.

Six years later, tiring of the whole venture, Mr. Seeger sold the house. It was bought by another American, Frederick R. Koch, of Koch Industries. Stanley Joseph Seeger Jr. was born on May 28, 1930, in Milwaukee, where his father was a prominent surgeon. The family’s wealth came from Stanley’s maternal grandfather, William Buchanan, who built a timber and oil empire in Texas, Arkansas and Louisiana.

While attending boarding school in Arizona, Stanley saw a traveling exhibition of works from the Museum of Modern Art in New York and developed a keen interest in art.

He studied music composition at Princeton, where he earned a bachelor’s degree in 1952 and spent a year with the Italian composer Luigi Dallapiccola in Florence. A fellow student was Francis James Brown, who later became Mr. Seeger’s collaborator in writing numerous works under the name Joseph James.

While working toward a master of fine arts degree in composition at Princeton, which he received in 1956, he began buying art in a serious way, mostly from the New York dealer Catherine Viviano, who represented the estate of Max Beckmann as well as a group of young British and Italian artists.

He lived in Greece in the 1960s and became a Greek citizen. In 1979 he gave Princeton $2 million to create a fund that supports the university’s program in Hellenic studies. In the late 1970s he settled, more or less, in London, where he met Mr. Cone, a staff member at Sotheby’s Belgravia branch, which specialized in Victorian art. He began buying older British artists like Fuseli and Turner, and moderns like Nicholson, Graham Sutherland, Malcolm Morley and Howard Hodgkin.

note these paintings have Sotheby's labels  

His whereabouts could be hard to pin down. At various times he lived on his 1929 yacht, the Rosenkavalier, sailing in the Caribbean or the Mediterranean. He also had, for brief periods, homes in Barbados and St. Moritz. After selling Sutton Place, he lived in country homes in Berkshire and Devon before finding his way to Yorkshire, collecting all the while. Quietly.

“One of the last things he did was to sell his Gauguin prints,” said Tobias Meyer, worldwide head of contemporary art at Sotheby’s, referring to a sale of 10 works on paper that took place in March. “It was a really wonderful collection he put together, but he never talked about