By Steven Kurutz
Oct. 18, 2017

In 1911, Robert Montgomery, a wealthy Philadelphia stockbroker, commissioned the architect Horace Trumbauer to build his family a home. He chose 300 acres of rolling pasture in an enclave northwest of the city called the Main Line, where, beginning around 1880 and lasting until after World War II, a portion of the American aristocracy lived out a version of English manor life on gentleman farms and large estates.

The Montgomerys may have been just another Main Line family saddling up for the Radnor Hunt and hosting parties for the Social Register set in the ballroom of their estate, Ardrossan. But they achieved a degree of fame beyond this clubby realm as the family that inspired “The Philadelphia Story,” the play and movie starring Katharine Hepburn as Tracy Lord, an irrepressible society girl (and proto-feminist) sorting out romantic entanglements on the eve of her wedding.

The real-life Tracy was Mr. Montgomery’s eldest daughter, Helen Hope Montgomery Scott. Her husband, Edgar Scott, was friends with the playwright Philip Barry, who visited Ardrossan many times and drank cocktails and was charmed by “the golden girl” who “rode to the hounds and was bright, witty and beautiful,” as Mr. Barry’s wife, Ellen, later remembered her.

The movie lends a mystique to the Montgomerys and the place where they lived and entertained, though since it’s been nearly 80 years since Hepburn was nominated for an Oscar for her role, that aura, like the blue-blooded dominion of the Main Line, is receding into history. A new illustrated book, “Ardrossan: The Last Great Estate on the Philadelphia Main Line” (Bauer and Dean), by David Nelson Wren, tells the story of the family and home in forensic detail.

We’re shown architectural drawings and old photographs. We learn that “an extensive selection of trees and shrubs” was “delivered and planted between May 15 and 18” of 1912. An entire drama, replayed in letters between Mr. Montgomery and the London-based decorating firm White, Allom & Company, is made of the delays in furniture deliveries. The whole thing boils over one day when Mr. Montgomery comes home and discovers yet again there is no hall table upon which to set his hat.

More than an estate, Ardrossan was a fief: At its peak it comprised roughly 760 acres, with several barns, outbuildings and a tiny village called Banjo Town, while the Big House, as the main residence was known, contained 14 bedrooms, nine bathrooms and 18 fireplaces spread over 33,000 square feet. The Montgomerys’ grown children lived in smaller houses on the property, as did the workers and their families who ran the estate’s dairy operation.

But the style was not ostentatious. In a phrase that perfectly articulates a certain old-money approach, the decorating firm was instructed that “everything was to be as plain as possible but of a quality unsurpassed.” It calls to mind a tidbit from Meryl Gordon’s recent biography of Bunny Mellon, the master of seemingly casual non-style style. The late heiress was known to offer guests at her Virginia farm a bowl of Lay’s potato chips, but behind the scenes she ordered her kitchen staff to first remove all the broken chips.

There is more than a whiff of pretense about the Montgomerys — in the way Mr. Montgomery insisted on being addressed as “Colonel” after his administrative service in World War I; in the large oil portraits of family members commissioned and hung throughout the Big House.

But Mr. Wren, who reveals in an afterword that he enjoyed cocktails with Helen Hope Montgomery Scott as a social visitor to Ardrossan in the 1990s, never writes in a tone suggesting anything but reverence. Nor does he probe into failed marriages or darker happenings, like when Hugo, the family’s long-serving butler, repaired to the pantry one evening in 1952, removed the house pistol from its drawer and killed himself. In the next paragraph, we learn that in 1953 Mrs. Montgomery bought a television — the first of its kind at Ardrossan — so the staff could watch the coronation of Queen Elizabeth II.

It can seem as if the intended readership for this lavishly produced book is the family itself, for who else would care that a favored meal of Mrs. Montgomery was tuna à la king? What ultimately engages the reader are not the privileges but the diminishments the Montgomerys experience in the march of time, as we all do, rich or not.

The war siphons off the estate’s male work force in the 1940s; later that decade, the Colonel dies and “the after-dinner boisterousness” is silenced. The seismic cultural shifts of the ’60s and ’70s erode the old formality. Large tracts of land are sold off to a developer (though the Big House remains in the family to this day).

You come to admire the Montgomerys for what they accomplished in spite of all this — gathering their family together on one piece of land for more than a century, building a house as a legacy. In this rootless, anxious age, that kind of solidity is aspirational. Mr. Wren’s exhaustive detail, it becomes clear, is an attempt to preserve, through every last landscaping receipt and cookbook recipe, a lost way of life.

A correction was made on Oct. 26, 2017: An article last Thursday about a book that explores the estate that inspired “The Philadelphia Story” misstated the honor that Katharine Hepburn received for her performance in the film. She was nominated for an Academy Award for her role; she did not win the award.