Ashton G. Gonella, personal secretary to President Lyndon B. Johnson and his wife, Lady Bird Johnson, at the White House with the president in 1966. She died July 12 at 85. (Courtesy of LBJ Presidential Library )

Ashton G. Gonella, a former executive secretary to Lyndon B. Johnson and his wife, Lady Bird Johnson, died July 12 at her son’s home in Kensington, Md. She was 85.

The cause was cancer, said a son, Geoffrey Johnson Gonella.

Mrs. Gonella, a Chevy Chase resident, became Johnson’s personal secretary in October 1957, when he was Senate majority leader. She assisted him through his last years in the Senate, his unsuccessful bid for the Democratic presidential nomination and his tenure as vice president, following him to the White House after John F. Kennedy was elected president in 1960.

She left briefly in 1962, after receiving an appointment from Kennedy to serve as director of women’s activities for what is now the Federal Emergency Management Agency. She rejoined the White House staff as Lady Bird Johnson’s personal secretary after Kennedy’s assassination in 1963.

“I called the Johnson house, the Elms, to see if I could be of any help,” Mrs. Gonella said in a 1969 oral history. “Mrs. Johnson asked me if I would come out and help them with telephones and mail because I knew the family and the personal friends.”

At the end of Mrs. Gonella’s first day, Lady Bird Johnson asked her to stay on indefinitely as her personal secretary.

Lady Bird Johnson was born in Karnack, Tex., about 30 miles from Mrs. Gonella’s home town of Shreveport, La., and the two became quite close. Mrs. Gonella traveled extensively with the first lady, coordinating her personal, professional and social activities until the end of Johnson’s presidency in 1969.

During an official visit in Thailand, the first lady confided to Mrs. Gonella that she had always wanted to swim in the Gulf of Siam (now known as the Gulf of Thailand). With the help of the Secret Service, Mrs. Gonella arranged a private swim for the two of them on a secluded beach.

“It was the most exhilarating experience I can remember,” Mrs. Gonella wrote in a personal history in 2000. “As we were treading water and taking in the ethereal sight, Mrs. J looked at me and said, ‘My, we’ve come a long way from Karnack and Shreveport, haven’t we?’ ”

She retained close personal ties to the Johnson family after she left the White House. Luci Baines Johnson and Lynda Bird Johnson Robb, daughters of Lyndon B. Johnson, both attended her funeral in Chevy Chase.

Ashton Glassell was born Jan. 13, 1929, in Shreveport. While serving as president of the city’s chapter of the League of Women Voters, she became known in political circles. She was a divorced mother of twin sons and was managing two floral shops in Shreveport when she interviewed for a secretarial position with Johnson.

“He couldn’t understand anybody with two children wanting to pick up and go to Washington and work for a Texas senator,” Mrs. Gonella said in 1969. “I think he took a gamble on me.”

After a three-month orientation in Austin, she moved to Washington to work on Johnson’s Capitol Hill office. She usually worked six to seven days a week in the office and often stayed around the clock to help during Senate votes.

“It was fascinating to see the way he would walk into the Senate floor and practically know what everybody was thinking and how they were going to vote,” she remarked in the 1969 oral history interview.

She sometimes took the brunt of Johnson’s quick temper. She recalled one such occasion in Jan Jarboe Russell’s “Lady Bird: A Biography of Mrs. Johnson” (2004), when Johnson snapped at her for serving him a lukewarm cup of coffee.

“No wonder you don’t have a husband,” he barked at her. “You can’t make a simple cup of coffee.”

Johnson was also a well-known stickler for detail, particularly regarding his staff’s personal appearance.

“When I came to work for him, I had long hair, which was the style at the time,” she told Johnson biographer Robert A. Caro in 2002. “One morning, he said, ‘You’re going to the beauty shop today, and you’re going to have 10 pounds cut off that.’ ”

Mrs. Gonella went to the hairdresser without complaint.

“That’s just the way he was,” she later said.

After leaving the White House in 1969, Mrs. Gonella briefly operated her own public relations firm before returning to Capitol Hill in 1971 as executive secretary to Sen. Lloyd Bentsen (D-Tex.) and later as a staff member of the Senate Labor and Public Welfare Committee. She worked in the office of the Senate sergeant at arms from 1976 to 1985.

She then began a real estate career, working for Shannon & Luchs and later Coldwell Banker until her retirement in June. She was a past president of the Maryland and D.C. chapter of the Council of Residential Specialists; a member of the Junior League of Washington and the Columbia Country Club in Chevy Chase; and a former deacon at Chevy Chase Presbyterian Church.

Her first marriage, to Roy Thornhill Jr., ended in divorce. Their son, David Thornhill, died in 2011. Her second husband, of 27 years, former Johnson aide and Washington Post golf columnist John Gonella, died in 1988. Survivors include a son from her first marriage, Ashton Thornhill of Lubbock, Tex.; two sons from her second marriage, Jon Gonella and Geoffrey Johnson Gonella, both of Kensington; 11 grandchildren; and four great-grandchildren.

In interviews, Mr. Gonella often spoke of Johnson’s concern and generosity toward his staff. Weeks before he left office, the president and first lady visited Mrs. Gonella in the hospital to meet her newborn son. Moved by the gesture, she gave her son the middle name Johnson.

“If you work for him, you’re practically a member of his family,” Mrs. Gonella said, “and he treats you that way.”