"My relatives are always telling me, 'Bring money.' I think it's the slogan of our family." The speaker erupts in a throaty laugh; his tanned face crinkles at the corners.

He is John Philip Sousa III, grandson of the legendary composer--and head of the family firm that keeps the royalties marching in. He's also the son of the late globe-trotting amateur sportsman, John Philip Sousa Jr., and the father of a one-time congressional candidate from California named John Philip Sousa IV.

He's clearly an American Express commercial crying out to be made.

"I'd do it. I'd do anything for money," he says, and giggles. "My brother Thomas always says--a little sourly, I think--'Well, John, you have The Name.' " He adds, "I have the Gold Card. And I've never had one damn bit of trouble with American Express."

Semper fidelis, he's keeper of the flame--especially the 80-or-so unpublished works that are protected under American copyright, plus such blockbusters as "Stars and Stripes Forever" and "The Washington Post March," which still make money in Europe. He keeps after music publishers for payments and, like Dow Chemical holding on to its cherished "Styrofoam," protects the Sousa name. "There was an Argentinian travel writer in San Diego using it as a nom de plume. We threatened him with a lawsuit and he stopped."

As president of John Philip Sousa Inc., he alone can allow would-be performers to play the unpublished music, decide which scholars can rummage through the private papers--and parcel out windfalls among the dozen Sousa heirs.

"We're always getting checks from unexpected places, like weird African nations I've never heard of."

Sousa is a hardy-looking fellow in his late sixties--"I never tell my age"--the shock of white hair very distinguished against the tan. He talks in the droll, flattened cadence of an aging preppy, and wears monograms and well-creased Brooks Brothers, accented by tassled loafers.

But he never went to prep school. Instead he spent much of his youth in self-education, wandering Cannes, Biarritz and Paris to discover the wonders of the Crusades and Marie Antoinette, before settling with his family in La Jolla, Calif. "I was never even aware that there was a depression on.

"As I look back on it," he says, "ours wasn't one of those families bound together by great warmth and sentiment. My mother had a rare talent for annoying people. The poor servants came and went. I had three sisters and a brother and we were all quite spoiled--all out to enjoy ourselves, flying around like potato chips on a high wind. I spent my days at the beach club. My father would be playing tennis or off in the valley, shooting quail. And, meanwhile, of course, my mother was firing maids.

"But I was very close to my grandfather. I used to visit him whenever I could." The "March King" died, at age 78, in 1932. Half a century after his death on tour with the Sousa Band in Reading, Pa., the parade goes on, making money for the heirs.

There's a musical in the works about Theodore Roosevelt and his daughter, "Teddy and Alice," with a score based largely on Sousa's tunes. There are new recordings of Sousa's marches, being distributed by the Book of the Month Club. There's also a chap named Keith Brion, who has been earning an increasingly handsome income impersonating the fierce-looking, bearded band leader in public performances.

And yesterday, Sousa III came down from New York on the Eastern shuttle to help the Library of Congress celebrate his grandfather's musical legacy by way of a book. The library--which has many of the composer's papers and original scores, including more than 100 marches, operettas, waltzes and songs--has just published a coffee-table volume full of pictures and essays, "Perspectives on John Philip Sousa."

The grandson has contributed a breezy reminiscence, writing, among other things, of going to the movies with his famous granddad: "At intermission a spotlight would be played on our box and my grandfather would stand to bow. Not to be outdone, I would do the same." He also tells about "fallout" from his famous name: "Two weeks ago I received the usual summons for jury duty. When my name was called in the jury room there was loud laughter from the other jurors. What was so funny? Nothing."

This afternoon at 3 on Neptune Plaza in front of the library's Jefferson Building, he'll be taking a bow in a program of martial music featuring the United States Marine Band, which his grandfather joined in 1867, giving his career a rousing start. But don't expect this Sousa to wave a baton. "My son leads bands all the time. He was on a March of Dimes telethon a few weeks ago. But I flatly refuse, and I'm not sure my son should either."

This Sousa, in fact, plays no musical instruments--"I guess I had a reaction against it when I was growing up"--and doesn't recall liking music at all until college. "My favorite piece was Beethoven's Violin Concerto in C minor," he says, and he'd play a recording of it over and over at Princeton.

While working at Time Inc. years ago, he wrote two books--"My Family Right or Wrong," which sold well, and "The Psychopathic Dog," which didn't--but hasn't done any more, he says, because "publishers no longer care about quality." He loves movies and old rococo movie palaces. His favorite Sousa march is "El Capitan."

Now a retired Time executive, he's just started up a hotel consulting business--"most hotels think it's enough to leave a revolting little mint on your pillow"--while trying to launch a newspaper column. He says the subject will be excellence. "I think I know what excellence is all about," he says. "It's appalling what we're losing in the way of style and class."

Sousa says, "I think there's a strain in my family in our enthusiasm to organize, from my grandfather right through to my son. My father was a master at organizing everything from a trans-Atlantic swim to a professional tennis tournament. When I was at Time, I was so well-known for organizing that I got hung up with arranging Harry Luce's funeral. And my son, when he heard there was a vacant congressional seat in Huntington Beach, Calif., immediately got an apartment there and ran a damn good campaign." He came in third in a field of 13.

On those rare occasions when his organizational talents fail him, Sousa says his relatives keep him on his toes. Once he made a minor error in distributing stock in John Philip Sousa Inc., and he tried to explain the problem to an older sister.

"I could just see her eyes getting narrower and narrower," Sousa said, and gave the throaty laugh again. "She was afraid she was getting short-changed."