A Lunch gathering where Nora Ephron was to be honored yesterday turned into a tribute to the writer a day after her unexpected death.

Ephron was to be one of 12 women feted at Casa Lever for AOL and PBS’ “Makers: Women Who Make America” documentary film series, along with Barbara Walters, Diane von Furstenberg, Gayle King and Katie Couric. But her passing shocked her closest friends.

“We’d known that Nora was ill, we didn’t know that she was dying,” said Walters, who revealed that she and Ephron were members of the Harpies — a close-knit cadre of lunching ladies who’ve met to eat and argue over 12 years at Michael’s, the Four Seasons and ‘21.’

Walters said of the gossipy group, “We would discuss face-lifts, other people’s. We just met with Nora, and she looked great.”

The Harpies’ ranks include Cynthia McFadden, power publicist Peggy Siegal, Condé Nast’s Maurie Perl and Beth Kseniak, former Hillary Clinton press secretary Lisa Caputo and Jennifer Isham.

But, “Nora was definitely the spiritual and intellectual leader,” Siegal told us, adding the Harpies will continue “with a heavy heart and an empty seat.”

READ NORA EPHRON’S 1989 POST STORY ON STEINBRENNER ‘THE BOSS TALKS UP A STORM’ (PDF)

The Harpies’ meetings always began with a half-hour devoted to discussing Hillary. “They’d grill Lisa on what country she was in, how tired she was, her hair,” a source told us. Next came the day’s headlines, and then the floor was open for intense debate.

“God forbid you were wrong, or you were dismissed and reduced to rubble . . . with great affection,” the insider said.

A line of luminaries went to Ephron’s apartment last night to pay their respects to her husband, Nicholas Pileggi, her sisters and sons Jacob and Max Bernstein, including Martin Scorsese, Barry Diller, Mike Nichols, Calvin Trillin, Joan Didion, Tom Brokaw, Gay Talese, Ken Auletta, Charlie Rose, Irwin Winkler, Bryan Lourd and Binky Urban.

A memorial is planned for Ephron on July 9.