He is tall, always well dressed, speaks with a delicious accent, and carries himself like Russian nobility. He can be seen at all the posh parties with a chiffoned lady named Garnett, and sooner or later, some female will ask, "Who is that goodlooking man?"

He is Baron Constantine Stackelberg, whose lineage, as they love to say, is lost in antiquity and is written in the histories of Russia, Germany, Estonia, Greece, England, Sweden, Austria and Spain. His and the late Earl Mountbatten's grandmothers were sisters. He is cousin to the late Queen Louise of Sweden and Princess Alice of Greece, not to mention the late Queen Victoria Eugenia of Spain.

Another Baron Stackelberg, a great uncle, at age 75 retired to Paris and took unto himself a mistress known as the "Kame au Camellias" . . . and of course, that little situation became "La Traviata."

Well, this well-connected gent turned 80 recently, and another cousin, the retiring German ambassador Berndt von Staden and Wendy, gave a party at their embassy residence on Foxhall where the surprise guest, Sandy Stackelberg, their only child, flew in from Europe, in his company's plane.

At the party, Guy Stark, a retired foreign service officer, was grieving over the loss of ancient trees at his Gibson Island home after Hurricane David blew through the Chesapeake. He was squiring Wilma McGinnis, widow of Ed McG., former Senate sergeant at arms.

Mrs. Claire Engel was with Dick Tribbe and speaking with Madelyn Bunker, who was wearing family pearls with twin magnificient diamond clasps. Jeannie Bryte had on diamond bracelets and ruby and diamond earring globs. Helene Williams had on one of her usual toga-like things and was wearing dark glasses.

The birthday progressed to Trudy Davis' house on Woodland Drive for a supper party.

Princess Eugenie de Smitt Olkhovsky Chavchavadze, who blithely introduced her husband (old Andover-Yalie) as "a retired spy" was there. In her decolletage she wore her great-grandmother's pendant and ropes of pearls . . . "Princess Nina of Russia's pearls" . . . adding, "My family is White Russian, and when I went to American Catholic schools, I tried to convert the nuns to Russian Orthodox."

Lady Delavel Cotter flew in from England . . . Dorothy Streisin, covered in jewels, came specially from Beverly Hills, where she owns the late Larry Harvey's house . . . the Stanley Sarnoffs . . . the Juergen Moritzes . . . Francy and Joe Smoak . . . Gretchen Poston and Mary Hoyt from the W.H. . . . Amb. and Mrs. Herz . . . Colonels Armanoff and Grasselli . . . Gen. Dawson . . . the Coopersmiths . . . the Firestones . . .

The day before the American Theatre Association's second annual costume ball, Olga and Marvin Esch (he's a former Michigan congressman) took over the whole 1925 F Street Club for a luncheon honoring the ATA board and workers, but particularly to introduce Judy Manos of New York, by way of Michigan, and associate producer of the smasheroo, "Sweeny Todd," which Marvin termed "the most successful musical on Broadway."

Judy and Leo Sullivan, press head of the KenCen, spoke passionately of their absolute favorite, Steven Sondheim, and much attention was shown Richard Coe, Washington Post drama critic emeritus, who was about to receive the ATA's award the next evening for his great contributions to drama over his distinguished career years.

Marvin, in his little speech, said, "It is quite unusual for a theater critic to come out at luncheon time . . . they always come out at night and are up to no good!" He described Manos as being "on her way as the key dramatic popular singer in America." She recalled her Washington debut at 'Way off Broadway with a group called "Gotham."

William Weckesser, a costume designer by trade, was a divine "Mad Ludwig" with feathers coming from everywhere, and had dressed Taylor Slamos in glittering red with trains and queenly high collars as the Queen from Snow White.

Leighton Stradley was in his Clan MacGregor tartan kilt evening attire . . . and the supremely lecherous "M.C." from "Cabaret" and Sally Bowes were really Frank Healey and Carolyn Stevens. Responding to a compliment on her long, Minnelli-type gams, Carolyn said, "Well, you see, I've been growing them for quite a long time."

Omar the Tent Maker himself couldn't have hung a floored tent off the low side of Woodland Drive, but Avignon Freres' man did . . . And it didn't slide off down into the ravine, either.

Tip O'Neill, House Speaker, was standing there telling of flying up that day to Boston with Rosalynn Carter, also wife Millie, to be there for the pope's triumphal entry into the U.S.A.

Hosts Senate Minority Leader Howard Baker and Joy were honoring his most famous Tennessee constituents . . . just about everybody who had ever tuned a guitar or hummed a hoedown or sung a lonesome-heart-in-the-night song at the Grand Old Opry.

All the country stars fell on Washington for the taping of the salute to country music at Ford's Theatre. Johnny Cash in black . . . so was June, but hers spiced with a Spanish shawl and that luxurious, almost-red hair pulled over into a large braid. She is so-o-ome sexy!

Mel Tillis wore Western duds, and honey, he don't stutter none, when he is talking to a big plateload of good eats. Larry Gatlin was shining in a cherry red satin, open-neck shirt with pale gray. Tom T. Hall was pure Opry clad . . . and Tandy Rice, thanking Joy "for a really good time," near 'bout ma'amed her to death.

Tennessee's other senator, Jim Sasser, and Mary were there as was Frank Moore, the president's head of Congressional liaison; CBS' Phil Jones and his wife; Bill Kovach, Washington New York Times bureau chief; and lots of Nashville producers and agents.

Joy Baker, daughter of the late Sen. Ev Dirksen of Ill., says she is selling her parents' Florida house, since both are now gone, but will keep the Virginia country place they loved so much, and where the senator grew his famous marigolds.

"I love that place, too," said Joy. "I could never sell it. It makes me feel simply wonderful just to go out there."