In the spring of 1976, a little-known but well-connected retail executive named Glenn Bernbaum opened Mortimer’s on Lexington Avenue at East 75th Street. At the time, Glenn was president of the Custom Shop, which sold made-to-measure men’s shirts, and it was said the restaurant’s name was in homage to the chain’s founder, Mortimer Levitt. On the other hand, there were those who said Glenn had borrowed the name from the storied high-WASP, old-money Mortimer family, many of whose members would become regulars at what quickly metamorphosed into Upper East Side society’s lunch-and-dinner canteen.

Glenn himself was part of a high-powered circle of “confirmed bachelors,” as gay men were referred to in those days, including the jewelry designer Kenny Jay Lane, the fashion designer Bill Blass, the department-store heir Steven Kaufmann, and the real-estate heir Jerry Zipkin, for whom Women’s Wear Daily coined the term “walker,” referring to the men who escorted society ladies to charity balls and dinner parties when their husbands were unavailable (or unwilling).

And where the walkers walked, the ladies followed.

Zipkin’s best friend was Nancy Reagan, and they could often be seen in deep conversation at the front table, lunching with their pals Pat Buckley and Nan Kempner. At that same table, partly visible from the street through sheer curtains, always sat Jackie Kennedy Onassis—not to mention Brooke Astor, C. Z. Guest, Judy Peabody, Estée Lauder, and Iris Love with Liz Smith. At dinner the cool, younger set took over, a mix of visiting Londoners and Park Avenue brats—Mark Shand and Harry Fane, Anne Lambton and Catherine Guinness, Whitney Tower, Averil Payson Meyer, Linda Hutton, Nenna Eberstadt. And let’s not forget Mick Jagger.

Jerry Zipkin, Glenn Bernbaum, and Anne Slater.

Glenn ran Mortimer’s like a private club—you either passed muster with him or found it impossible to make a reservation (let alone walk in off Lex). The décor was as bare-bones as any Calvinist chapel—brick walls, hardwood floors, bentwood chairs, white cotton tablecloths with small centerpieces, peonies or hydrangeas or roses the only hint of luxury. The food was clubby, too, though delicious: chicken hash, meatloaf, creamed spinach, bay scallops, and shad roe in season. It was also reasonably priced, because, as Glenn famously noted, no one likes a bargain more than the rich.

And now it’s all in a splendid book, Mortimer’s: Moments in Time, by Robin Baker Leacock, with photographs by Mary Hilliard, a preface by restaurateur Robert Caravaggi, and a foreword by society writer David Patrick Columbia.

The private-party guest lists and engraved menus, the daily reservation books and food and wine suppliers’ bills, the handwritten thank-you notes from Sister Parish and Jack Pierrepont, the typed ones from Mike Wallace and Malcolm Forbes, Glenn beaming beside everyone from Marie-Hélène de Rothschild to Helen Gurley Brown, Henry Kissinger to Swifty Lazar: it’s all there.

One of my most vivid Mortimer’s memories is of a small dinner that Reinaldo and Carolina Herrera gave for Princess Margaret in 1983. As we stood from the table to leave, Glenn had “God Save the Queen” played on the sound system, and the scotch-soused younger sister of the Queen gave the little royal wave to everyone in the restaurant. —Bob Colacello

Bob Colacello is at work on a biography of Nancy Reagan, and is an Editor at Large for AIR MAIL