LADY SONDES IS SELLING HER PARTY PLACE FOR $5.5M

WHENEVER Lady Sharon Sondes threw open the doors of her Park Avenue apartment for her cocktail fetes, hundreds of her socialite friends would fill the place to capacity.

The so-called fanny-bumpers were usually called for 6:30 and meant to be two-hour affairs, but instead would often last till midnight.

Sondes once told our Neal Travis that she was never enamored of bashes thrown in restaurants.

“You should have people into your home,” she said – and the usual fun crowd of actors, writers, producers and bright young things were always wall to wall at her place.

Now Sondes is asking $5.5 million for the grand co-op at 555 Park Ave. – a place she’s owned for decades, since her mother purchased it for her when she was a young adult.

Sondes’ mother was a prominent interior decorator and hostess, Ellen Lehman McCluskey, whose family founded the Lehman investment house, and she added her own deft touches to the young Sharon’s apartment.

The elegant 3,500-square-foot pre-war digs features extraordinary details, including mahogany accents, hand-painted décor, high ceilings and a gourmet kitchen.

“She doesn’t spend enough time there anymore to make it financially viable,” says a source, citing the $4,200 monthly maintenance, among other expenses.

Sondes now divides her time among several other domiciles – in the Hamptons, Palm Beach, Fla., and her Colorado ski chalet.

There’s at least one more shindig, though, and it’s tonight, when some 400 guests will celebrate the 70th birthday of Hollywood and Broadway producer Marty Richards.

According to social chronicler David Patrick Columbia, Sondes knows how to entertain the swells.

He says her last party featured piles of little tea sandwiches, guacamole and delicately fried egg-rolls that Sondes’ lifelong housekeeper, Luz, turned out by the dozens – perfect accoutrements for those gin-soaked soirees.

The blonde and elegant Sondes grew up in the Park Avenue building, and eventually became the Countess Sondes, after marrying her fifth husband, an English lord Earl Sondes (now deceased), whom she later divorced.

Her current companion is jeweler Geoffrey Thomas, a charming chap she calls “Mugsy” and has dated for several years.

Sources say Sondes’ uncle, Orin Lehman, owned the apartment prior to Sondes, and entertained such notables there as Eleanor Roosevelt and Greta Garbo.

He was for many years the commissioner for Parks and Recreation for New York State and the president of the New School.

Orin was married to Wendy Vanderbilt, who he eventually divorced.