"If I knew he was from Dallas I would have looked him up," said Scooter Miller as she climbed the stairs to the Gordon Conway show.

Not so easily. Conway, who was, incidentally, a she, died in 1956. About 200 of her narrative drawings, fashion illustrations and motion picture and theater designs were previewed last night at Octagon House, in a show that will continue through July 20.

Miller was not alone in her perplexity. It was a great evening for Gordon Who? Few guests who came to admire the work of the artist who attended the National Cathedral School and, until she was tapped by Conde Nast art editor Heyworth Campbell, expected to become a concert pianist, had any idea who she was or what sort of things she did.

Even Jeanne Butler Hodges, head of the American Institute of Architects Foundation, knew nothing of Conway when she discovered her work. She was merely returning pieces from the Octagon's Dolley and James Madison show to Mount Sion, the house built by Madison's grandfather.

"First I saw three Erte sketches hanging in the den at Mt. Sion. The incongruity of the sketches hanging with the beautiful 18-century antiques made me ask the Marshall Allens if there were any more," said Hodges.

Olive Johnson Allen, Conway's second cousin, showed her first a folio, then eventually the total archives -- 2,000 pieces of drawings, diaries, letters and magazines -- plus clothes of Gordon Conway, who had lived in Mount Sion for more than two decades. Ten trunks full of Conway clothes had been discarded because of mildew.

Last night, for the opening party and seated dinner for 200 that followed in the garden at Decatur House, Hodges was wearing a hand-beaded dress that belonged to Conway. Robin Jacobsen was wearing a printed style so close to one of Conway's illustrations it was thought to be a Conway original.

For the exhibition, which is sponsored by Philip Morris Inc., mounted by Jenny Moran, four Conway fashions were made by costume creator Barbara Mattera, including one from The Tatler, and a daring breast-baring dance frock created for the play "Wonderbar."

It was a sketch of a red hat for the Tatler that sold Odile Basch, Philip Morris' culture affairs manager, on sponsoring the exhibit. "It was a new name to me," she admitted. "But the drawing of the red hat and the art moderne figures seemed right in keeping with our Virginia Slims image."

Robin Jacobsen had never heard of Gordon Conway till she was "introduced" by Jeanne Hodges. "We were just born in the wrong time," said Jacobsen, who drifted easily around the room in a Conway dress. "The clothes are so much in the spirit of the feminine body," she said.

If so, why hadn't anyone heard of Gordon Conway before last night? Art historian David Schaff, who acted as curator for the show, called "That Red Head Gal," thinks it's because she worked in so many media. And because her most productive period ws spent in Europe.

"She had inherited the family place in Virginia," said her cousin, Mrs. Allen. "She just wanted to come home and rest."