As Maryland's Acting Gov. Blair Lee III was leaving by the front door of his Silver Spring home for a chauffeured ride of Annapolis, his wife, Mimi - in blue jeans, denim work shirt and sneakers - was hauling canoe paddles out the back door to an old Impala station wagon.

Mimi Lee, sporting red sneakers, carrying a bag lunch and hitching a six-slot canoe trailer to her car, was an unusual sight in the Maryland tradition of governors and first ladies.

While Blair Lee's life changed dramatically in early June when Gov. Marvin Mandel relinquished temporarily his office because of illness and the pressures of his trial on political corruption charges, little has changed for Mrs. Lee.

She still answers her own telephone, vacuums her house, cooks for her guests. She disdains luncheons and fashion shows except for her favorite causes - the Red Cross, water safety and Holy Cross Hospital among others. And while some other women from ordinary backgrounds would revel in the new status. Mimi Lee admits that sometimes it's convenient.

She is no less well bred than her husband, the scion of a patrician Montgomery County family, but the word "aristocracy" applied to her upbringing makes her grimace. "Don't make me throw up!" she says when it is used.

An ambassador's daughter who lived in 10 countries before college, an only child until she was 18, a Bryn Mawr graduate who began a brief career as a chemist before she married and bore eight children - and the wife of a man who wears politics like a glove, Mimi Lee is on her own."

"She doesn't go around saying, "I'm Mrs. Blair Lee," said Lee Fisher of Silver Spring, who has known her several years. "She says, 'I'm Mimi Lee.' She's her own person."

Her long graying blond hair swept off her face and knotted high at the back of her head. Mrs. Lee flashes frequently a full easy smile that sets off her high checkbones and handsome Katherine Hepburn looks. She is tall, sturdy-looking, a woman in charge. Her blue eyes are always at attention.

"I'd rather die than sit in meetings . . . I'm frustrated by a great deal of conversation and little doing," she said!

She espouses physical activity for herself and others as excellent for morale. She swims three times a week at the Silver Spring Y and recently took up yoga.

When Mimi Lee is "doing her own thing" - a notion she personifies - she usually is enjoying it like a Pied Piper merrily attracting anyone of any rank or men to join her and often teaching these skills to others, including the handicapped.

"She's basically in the business of helping people," said one of the Lee's sons, Fred.

Until now, Mrs. Lee has been able to preserve her private life - the volunteer activities, sports, reading and the solitude she cherishes. Politics have belonged to her husband. Much of the enforced social life that comes with it, and the Lees minimize, is "work" to Mimi Lee, who grew up in the diplomatic corps.

"In the foreign service set, social life never struck me as all that enjoyable. It was part of the job," she said. Politically, she has confined her activities to only the very "necessary" functions.

"I don't think I'm that vital to Blair's political life," she said. "He's quite a capable person. After all, he's the governor not me."

Mimi Lee is the opposite of Jeanne Mandel, who did not grow up amid wealth and whose penchant for political sparring is so evident that she has become a political topic herself. Nor does the acting first lady call to mind earlier governor's wives, like Judy Agnew, dutiful in the tradition of her husband's helpmate."

She considers much of politics "frivolous." "I'm not politically knowledgable," she said. "I work on common sense.

She is, however, a good sport about the increasing demands on her time as the acting governor's wife and fulfills the command performances gracefully, with charm and good humor. It was a disappointment, she conceded, when she had to give up longstanding plans for a whitewater canoe trip on the Shenandoah River for the recent Maryland visit of Princess Anne of England. The day turned out to be "lovely" after all, she said.

"I'm not sure the expectations (of politicans' wives) aren't based on styles that are perhaps outmoded," she philosophized. "I'm looking at different styles right now."

Blair Lee chuckles when the subject is raised, indicating no hint of disagreement. "I have no desire to have her plunge into the middle" of his political life, he said.

Born "Mathilde" on May 1, 1920, in the District of Columbia, "Mimi" Lee was named after her paternal grandmother, a woman of French and Spanish heritage who was related to Christopher Columbus. Her father, Pierre de Lagarde Boal, was a diplomat whose assignments included ambassadorships to Nicaragua and Bolivia. Her mother, Jeanne de Menthon, a French woman who is related to the family that trained St. Bernard dogs for Alpine rescues, still lives on Lake Geneva, Switzerland.

As a Girl Guide in Canada, where she attended the private Elmwood high school in Ottawa, Mimi Lee was presented her first canoe, a red wooden one she still uses.

The Lees and the Boals were family friends for years and Blair and Mimi married July 6, 1944. Within 13 years, they had seven boys and one girl.

Most of the child-rearing was left to her. As a mother and a Girl Scout leader, she was clear about her standards but encouraged others to reach their own conclusions, to think and act freely. She brought her children up as Catholics like her (Blair is Episcopalian) but ultimately it dawned on her that going to church rigorously "put me in the worst humor." Now she stays home from church.