On her 61st birthday in 1989 Ann Russell Miller threw a party for 800 guests at the Hilton Hotel in San Francisco. Friends flew in from around the world to dine on caviar, coquilles Saint-Jacques and chicken in beurre blanc sauce while being entertained by a live orchestra.

A widowed heiress with ten children, Miller led a packed life as a Californian socialite, hosting dinner parties at her opulent nine-bedroom house overlooking San Francisco Bay. She smoked, drank champagne, played cards, spent five hours a day on the telephone and, as an expert scuba diver and enthusiastic skier, traveled around the world. She had a season ticket to the opera, was a high-society patron of many charitable causes and drove her sports car at such reckless speeds that, according to her son Mark, “people got out of her car with a sore foot from slamming on an imaginary brake”.

Yet the party at the Hilton was not just another sybaritic event in her social whirl. Guests had been summoned to bid her adieu, as she was about to leave the material world behind.

At the party she wore a flower crown and carried a helium balloon with the words “Here I am” so that people could find her amid the throng. It was, one guest said, like a funeral with much weeping, except that the subject of their tears looked “serene and happy”.

Ann Russell Miller as a young woman in her parents’ home in San Francisco, 1948.

The next day Miller flew to Chicago and joined the Sisters of Our Lady of Mount Carmel as a novice, part of the novitiate. She spent the next three decades living in the order’s Illinois nunnery as Sister Mary Joseph of the Trinity, exchanging her Hermès scarves and Versace shoes for a coarse brown habit and sandals, and her social life for vows of poverty, chastity and obedience.

The hours she had spent on the telephone each day to friends such as Nancy Reagan and Bob Hope were replaced by round-the-clock silence and prayer. Her bed was a wooden plank covered by a thin mattress in a cell. She never left the convent again or had any further physical contact with her children and grandchildren. The Carmelite order is a secluded one and although she was permitted one visitor a month, touching and hugging were forbidden. Meetings were conducted with two sets of grated metal bars separating her from her visitors. Her son Mark described it as “the absolute antithesis of how she lived her life up until then”. One of her 28 grandchildren (many of whom she never met), Jane, used a more colorful analogy: “It was like The Great Gatsby turned into The Sound of Music.”

At the party she wore a flower crown and carried a helium balloon with the words “Here I am” so that people could find her amid the throng.

Some thought she was behaving irresponsibly. Others were puzzled by the spiritual call that led her to renounce her worldly possessions. More than a few predicted she would soon give up the rigors of monastic life and return to her old ways.

The order demands five years as a novice before taking final vows. She became a bride of Christ in a ceremony in the convent’s chapel in 1994, which made national news. After that her celebrity quickly faded as she devoted herself to prayers and contemplation.

After meeting Richard Miller, she put her childhood dreams of becoming a nun on hold and embraced the life of a well-to-do wife.

The reactions of her family were mixed as some struggled to accept her calling and others embraced it. Her own mother, who lived to be 99 and died after Miller had entered the nunnery, was said to resent her decision, and one of her sons likened her retreat to a bereavement. Yet Miller’s oldest daughter, Donna, believed she had made the right choice. “A lot of people thought it was selfish to leave her mother and her children, but I don’t think it was,” she said. “Moderation was not in her vocabulary. She did everything full-bore. She really needed this change in her life.”

Even from the nunnery she still managed to keep a close watch on her children, writing them long letters in which she urged them to follow a righteous life. Those who divorced and remarried were banned from a family property over which she retained control through some of her daughters. She consoled herself by praying for them.

“I understand why people don’t understand,” her daughter Janet said. “For those who have faith, no explanation is necessary. For those who don’t, no explanation is possible.” When Janet first saw her mother through the visitors’ grille, she thought, “This is where she’s supposed to be.”

Perhaps unsurprisingly she was something of an idiosyncratic nun. She could not sing, was notoriously late for her chores and duties, and broke the rules in countless small ways such as playing with the convent’s dogs and throwing sticks for them.

“She was just a lot of fun. She had all kinds of stories from her past life that we were happy to hear,” said Mother Anne, the present prioress who has lived at the nunnery since 1966.

Sister Mary Joseph is survived by her ten children from her marriage: Donna, Douglas, Richard, Janet, Marian, Leslie, Donald, David, Mark and Elena.

Born Ann Russell in San Francisco in 1928, she was the daughter of Catholic parents, Louise (née Herring) and Donald Russell, the chairman of Southern Pacific, which ran the railways in much of the western US. Her only sibling, Donna, died at a young age.

Expensively educated at the Spence School in New York and at Mills College in Oakland, California, she had dreams of becoming a nun, but fell in love. She ran away aged 20 to marry Dick Miller, whose family had founded the Pacific Gas & Electric utility company. At her wedding George “Corky” Bowles, another admirer, kissed her on the cheek and told her: “I will wait for you.”

When her husband died of cancer in 1984, Bowles invited her to join him on his yacht in the Mediterranean and proposed. “Don’t be ridiculous,” she told him, for by then she was already determined to take the veil.

Miller had 10 children, an equal number of each sex. She joked that it was a true example of planned parenthood.

By the age of 27 she had five children and she went on to have five more. With an equal number of each sex, she joked that it was a true example of Planned Parenthood. Devout in her faith, she went to Mass daily, took a priest with her on her holidays and sternly applied her religious principles to her family. One son was kicked out at 18 and told not to return to the family home because she disapproved of his relationship with a married woman.

She made a pact with her husband that when one of them died, the other would join a religious order, and together they visited the Carmelite convent in Illinois where she would end up living. She wrote in the guestbook “Save a place for me”.

After her husband’s death she duly called her children together at two separate lunches at Trader Vic’s restaurant — one meal for the boys and another for the girls –— and told them her plan. They knew there was little point in trying to dissuade her.

She gave away her designer clothes and Imelda Marcos–like collection of shoes, sold her San Francisco mansion to a member of the band Metallica, and metamorphosed into Sister Mary Joseph of the Trinity.

“The first two thirds of my life were devoted to the world,” she said. “The last third will be devoted to my soul.”

Sister Mary Joseph of the Trinity, socialite turned nun, was born on October 20, 1928. She died of complications after a series of strokes on June 5, 2021, aged 92