"No politics, no politics," her friends said. "This is a celebration, not a political event." But Ersa Poston, at yesterday's lunch honoring her as she retires as vice chairman of Merit Systems Protection Board, didn't agree. "I'm out now, so I can say what I want," she insisted, and proceeded to do just that.

"A lot has changed," she said before the lunch began, "but I'm a little upset. I'm not sure I agree with the figures that tell us black women are rising in government. I see a diminishing level of black women in strategic positions where they can serve as mentors for both black and white younger women."

Poston was speaking from the experience of her early years with the YWCA, her work with then-governor Nelson Rockefeller as the first black woman member of the New York State cabinet and finally as one of the highest-ranking black women in the Reagan administration--although she was appointed by Jimmy Carter.

"Black women especially are, I'm afraid, getting to feel much like the unemployed," she said. "We're frustrated, angry. 'Who is really listening?' That's the question we ask."

Women's role in government wasn't the only political subject Poston broached during the luncheon friends organized at the Madison Hotel, where more than 160 of them gathered. At one point during the lunch, when jokingly told that her friends had filed a temporary restraining order to ensure she would remain in Washington after her retirement, Poston snapped, "I'll be sure to hire two very good lawyers: Brooke and Jordan!"

She was referring to former senator Edward Brooke and former president of the National Urban League Vernon Jordan, both of whom spoke during the afternoon. The two are now advising opposing camps in the split between the NAACP and the NAACP Legal Defense and Education Fund. The audience greeted her sally with roars of surprised laughter.

"We are here to thank Ersa," Jordan told the crowd, "for all the advice and counsel, and the cussin' and fussin' she gave us." He waited for the laughter to fade. "And I know what that advice is like from personal experience. Civil rights organizations have not always been as equal towards women as they should have been," he said, smiling as the women in the audience called out their assent, "and Ersa has helped to change that. There are many across the country who don't know her name but who owe a debt of gratitude for the changes she has made, for the policies she has written."

Brooke, in his tribute, said, "I just wish my party had had the good judgment to have appointed Ersa to at least a Cabinet position. Not because Ersa needs it, but because the country needs it. We now talk about the liberated woman. Ersa was liberated at birth."

In her work with the Merit Systems Protection Board, on which she has served since its creation in 1979, Poston, 62, has participated in overseeing the health of the federal personnel system, by adjudicating disputes brought by civil service employes.

At first Poston walked from table to table greeting friends who had traveled from around the country to honor her. She finally sat down when Marjorie Parker, one of the lunch's sponsors, announced that the salad, which the guest of honor was missing, had been created for the lunch and was called "Ersa's Surprise."

Once Poston had told the government, as she put it, to "take this job and shove it," she took two weeks off--"the longest uninterrupted vacation of my life." Already she is anxious to get back to work and plans to organize private sector help for third-world problems.

"While you're a public official you have to contain your emotions in order to appear objective," she told her friends as her voice began to shake. "Now I don't have to impress a damn soul. When you retire you can still join those lines and speak out. For the first time in Ersa's life, she is going to do that."