Above all, the Lunts were perfectionists.

Nothing better reflects this characteristic of the celebrated acting couple, Alfred Lunt and Lynn Fontanne, than their two final performances in Terence Rattigan's "O Mistress Mine." They had opened it in London as "Love in Idleness" in late 1945, and by the time they reached Washington's National Theatre they had been playing this light-as-a-feather comedy four years ("might as well be reading the phone book," cracked one New York critic). But there was a spot in Act II where both were confident a laugh should be that was never coming.

On the final Saturday matinee, that laugh came. They spent the few hours before the final performance that evening alternately thrilled and worried whether they could capture it again. The cast gathered in the wings to watch. And the laugh came, Alfred convinced it was from a quick turn he'd made. After their final performance of four years, the Lunts wired Rattigan they'd found it.

On Saturday, at the age of 95, Lynn Fontanne died at the same Wisconsin home where Lunt had died on Aug. 3, 1977.

They had a unique elegance. Fontanne's costumes set fashions and her public image, from the days she appeared as a newcomer at Frank Crowninshield's posh parties, was of arresting, simple elegance, her hair pulled far off her face, her long, fabulously slim fingers jeweled but chastely so, and, usually, pearls around her swan-like neck. She seemed to amble rather than to walk, her knees giving a little, her back arched, shoulders back, immensely at ease.

Cecil Beaton told of working with her on costumes, months and months of getting just the right colors and materials to gleam under the lights. "Lynn and I went home in a taxi. She put her feet up and laughed: 'Why do we do this--all in the name of fun? It's never fun. It's damned hard work and we fight a lot, but it's interesting and exciting and if we win through, it will all have been worthwhile.' "

This perfectionism--the overlapping of lines that virtually became a trademark, their demands of precise lighting and colors, their care over supporting casts--was screened from general awareness. For months before the opening of a new play, they'd rehearse at Ten Chimneys, their Genesse Depot, Wis., home imagining the characters they were to play, literally living each day as those characters, walking, speaking, behaving as the gradually evolving people would behave. By the time rehearsals began each knew exactly what the other was thinking.

Surprisingly, both inclined toward nervousness, although it was never apparent on stage. When they were trying out Behrman's "I Know My Love" at Washington's Gayety, Alfred, whom I'd barely met, called to ask: "Do spend the day with me. We can talk theater, which will keep me from thinking about Ivor Novello, who had died that morning in London and Lynnie's arm being in a cast." (She'd hurt it in a backstage accident.) Later Alfred said in his dressing room: "I'm so worried about Lynn" and in a few moments, Lynn, in hers, would say: "I'm so worried about Alfred's cold."

Their discipline showed on stage, but such practitioners of the then-fashionable Method as Lee Strasberg snorted: "A man like Alfred Lunt has more equipment as actor and director than Laurence Olivier. But what do the Lunts do? Fool around with tired Noel Coward."

Privately, never publicly, the Lunts reflected: Don't people understand the nature of comedy, that it is written by serious men whose hearts were so broken by life's tragedies that they laughed in order that they might not go mad? Don't people see that beneath the laughter of Shaw and Giraudoux, of Chekhov, Molnar, Behrman, Barry, Sherwood, Coward and Rattigan there is a deep sadness about the human condition?

They'd played them all and Shakespeare, too, their prankish production of "The Taming of the Shrew" shocking the pedants.

Fontanne's first and final appearances on American stages were 69 years apart in Washington, at the vanished Belasco on Lafayette Square in 1910 and at the Kennedy Center's Terrace Theater in 1979 as Irene Ryan Night's guest of honor in the American College Theater Festival.

That first American venture in "Mr. Preedy and the Countess" ended after 24 New York performances and she went home to England, where she had been born in Essex of a French father and Irish mother. Her father was a designer of printing type who dreamed of a leisurely, literary life and read Shakespeare to his five daughters. At 17 she managed to meet Ellen Terry, the great actress of her day, and Terry got Fontanne her first role in 1905, a Drury Lane Christmas pantomime.

Newsman Hayden Talbot once told me how Laurette Taylor, making her smashing London bow in "Peg o' My Yeart" in 1913, needed someone to show her the social ropes, "etiquette." Norma Mitchell, then Mrs. Talbot, recommended Fontanne, a game little actress everyone admired but who never seemed to wind up in a winning role.

So it was that Fontanne made her second voyage to America and fairly early recognition. In the summer of 1919 George C. Tyler, Helen Hayes' producer, planned a series of five new plays at Washington's National with Hayes, Cornelia Otis Skinner, Sydney Toler (later the movies' Charlie Chan), Glenn Hunter and Alfred Lunt. Those were in air-conditionless days and with the "Temperance" drive in full force, Tyler cut the five weeks to three.

But one of those, "Made of Money," by Porter Emerson Browne and Richard Washburn Child, marked the Lunts' first appearance together, although it was a few years before Molnar's "The Guardsman" united them almost constantly. During that Washington June, when they were playing in "Made of Money," Helen Hayes recalls: "We didn't see much of either of them. After he heard her voice on stage and she watched him fall down a flight of stairs, they were taking carriage rides in Rock Creek Park."

The summer of 1920 was memorable, when Fontanne had a role in "Chris" by Eugene O'Neill. It was a short play, tested in Atlantic City, and she told the author that the mother as a rosy concept was quite wrong. While she was acting in "Strange Interlude," O'Neill told Fontanne that her remark about the mother role had inspired the play she was performing. Rewritten, "Chris" became "Anna Christie" and Pauline Lord got the part.

So followed the years of teamwork and gathering glories. The Lunts toured the nation and if the sets and costumes didn't arive in time, they'd do the play anyway. That faithfulness in touring made them national favorities and, though they did a couple of films and a few TV performances, their celebrity lay in their faithfulness to national stages.

Their lives were rich in friendships, among the least likely of them George Burns and Gracie Allen. "We caught them one matinee in London," Lynn recalled, "and kept going back to watch their eerie timing."

After Alfred's death she flew the Concorde to London to see whether she might live there, but after a few months returned to Ten Chimneys, where she resumed her two-mile walks and flower-tending, interspersed with occasional visits to friends in New York and Denver. Players and stage managers, technicians and hairdressers were often on the phone keeping her abreast of the gossip. To Alan Hewitt, long a member of their company, she gave one of Alfred's gold cigarette cases and mementos spread from coast to coast. I had my last letter from her only a couple of months ago, though it was signed by her secretary.

Always there was the laughter intended to cover sorrow. When her longtime attorney, producer Donald Seawell, went out to her immediately after Alfred's death, she came down the staircase in white hair. She fluffed it out and laughed. "I should have had it done years ago." At 88, she was suggesting that the white hair hadn't come naturally, that she'd had to have it "done." It was an elegant, theatrical and gallant message from the sorrow inside. Exactly in keeping with the Lunts tradition of impeccable sang-froid.