NO ONE WHO knows Polly Shackleton well and we are proud to count ourselves in that considerable number -- believes for one minute that she is retiring from service to this city. Not once in more than 30 years of remarkable changes in the life and times of Washington did it ever occur to Mrs. Shackleton to back away from the political battles for genuine home rule in the District of Columbia or from her deep commitment to "some of our most vulnerable citizens." But she is ending a formal -- and formidable -- career as a member of the District of Columbia Council since its first days as an appointed body.

It has been an unlikely story all along. There in the 1950s -- as a southern town of two segregated worlds was seeing a dramatic growth in its black population and in all the pressures on government that this change would entail -- was this white woman of some means who crossed racial lines to stand up for local self-government and for social services and justice in every neighborhood. By no means a polished orator and never one to toot her political horn, Mrs. Shackleton spoke through her presence whenever and wherever it counted -- and the poor and the disenfranchised came to recognize that her commitment was real.

Still, some wondered, how long would this woman who certainly didn't need this kind of work keep at it? In 1967, President Johnson -- after a monumental but losing effort to win passage of a home rule bill for the District -- created an appointed "mayor" and council for D.C. Mrs. Shackleton was an early and easy choice for a seat on the council. By then her ability to cross racial lines and press for what are now called "human services" for all had won her exceptional respect.

But would it transfer to the elective process for which she had fought so hard? "Charisma" wasn't something you would list among her attributes for electability. On the contrary, her candor could be as disarming as her open conduct of public business. But she won the seat from Ward 3 in 1974 and hasn't been touched by opponents since. Her representation of the city's whitest ward has not suffered from any "liberal guilt" on her part, but has won the understanding and support of colleagues who know her constant interest in and influence on efforts to help all residents: "children suffering from abuse or neglect; the mentally retarded; incapacitated adults, especially the infirm elderly; and residents of nursing homes and group homes."

Among the tributes to Mrs. Shackleton this week was one particularly impressive compliment from someone who has worked with her ever since he came to town as a civil rights organizer. "Her word is her bond," Mayor Barry said. And her contribution to what has become better about Washington has been unique.