Think London theater and, for much of the 1980s, the megamusical came to mind, as show after show wowed the West End before taking on Broadway and the world.

Return to the topic now and the preferred word might be flop. The once-bullish genre is passing the baton back to Broadway, which is generating musical hits of the sort London can only imagine.Consider the following:

- Last year saw the near-simultaneous closings on both sides of the Atlantic of "Sunset Boulevard," the Andrew Lloyd Webber musical whose international losses have been estimated as high as $50 million.

- Feb. 28 is the last performance after 20 months at London's Prince Edward Theater of "Martin Guerre," a $7 million failure from producer Cameron Mackintosh, who not long ago was considered the leading musical Midas of the West End and Broadway.

- On March 28, the current revival of "Jesus Christ Superstar" calls it quits at the Lyceum, having paid back a scant 15 percent of its $6 million-plus cost. Its producer? None other than Lloyd Webber, who composed the rock opera more than 25 years ago.

To be sure, London, like Broadway, has always had flops - shows that open and close so quickly that the paint on the theater marquee doesn't have time to dry.

What's different about the higher-profile misfires is that they come from the two men - Lloyd Webber and Mackintosh - who set the global agenda for musicals throughout the 1980s with such still-vibrant money-spinners as "Cats," "Les Miserables" and "The Phantom of the Opera."

There hasn't been a commercially successful new English musical to play the West End since "Miss Saigon" - and that was nine years ago.

These days, both men can merely look on as the likes of the Disney Co. and Canadian producer Garth Drabinsky's Livent reinvigorate Broadway with such musicals as "The Lion King" and "Ragtime," even as the West End's biggest new hit is the London version of Broadway's smash revival of "Chi-ca-go."

The fact is, Broadway may be booming musically, but it no longer has the British to thank.

"What you've got suddenly is all sorts of different artists firing on different fronts," Sam Mendes, the English director who makes his Broadway directing debut next month with a revival of "Cabaret," says about New York. "There's still an excitement generated by big-scale, big-cast musicals that just doesn't happen in London."

Indeed, the current London trend is to think small, or at least smaller. Lloyd Webber's next show, "Whistle Down the Wind," will open July 1 at the Aldwych, a theater generally given over to plays.

And whereas the adaptation of the Mary Hayley Bell novel and subsequent 1961 film once was intended as a big Broadway deal, the West End version has been scaled back to a $3.6 million production, less than half the original American estimate.

"Everything I've ever done has always been when we didn't have the money to do it, or it was at least a real fight," Lloyd Webber recalled in a recent interview at his London home.

Costs, the composer-impresario said, have spiraled out of control, an assertion borne out by the abortive Washington, D.C., tryout of the same show just over a year ago.

"We spent nearly $150,000 on a baptismal font for a moment which was, in my view, interrupting my song anyway," he said. "For something that lasts exactly three seconds, you say to yourself, `What on earth are we all playing at?' "

The composer also noted that some $35,000 was spent sending around scores. "When we did `Cats,' we took them on the bus, or I took them in a taxi," he said.

And while Mackintosh insists that Frenchmen Alain Boublil and Claude-Michel Schonberg, the creators of "Martin Guerre" and "Les Miserables," have "probably two to three more musicals in them, with me anyway," his next projects will be cushioned by first appearing in the not-for-profit theater, mostly in the United States.

"I'm not frustrated," Mackintosh said in an interview before flying to New York for the 10th anniversary of the Broadway opening of "The Phantom of the Opera."

"Look, it's the reality," he said. "There aren't many shows in history that are blockbusters. Some become phenomena, and others don't. There's that elusive thing that makes a smash hit musical, and nobody can foretell what it is."

It would be easy to argue that the ongoing success of, say, "Cats," with its "now and forever" advertising tag line, has warped musical expectations with the result that everything now has to run decades.

" `Porgy and Bess' ran 135 performances on Broadway," Mackintosh said. " `Sweeney Todd' ran eight months in this country. `Pal Joey' took 20 years to be reclaimed.

"Listen, whether or not `Martin Guerre' is one of those shows, we won't know for 10 or 20 years. If the theater were only driven by how much money a show had made, we would have no theater."

Lloyd Webber was sounding a similar refrain: "If you set out to write a piece of music, you don't say what it is you expect it to do in terms of a run."

As an example, Lloyd Webber cited his roller-skate musical "Starlight Express," a show first written for fun. "It was a trifle and a throwaway," he said. On March 27, "Starlight Express" starts its 15th year at the Apollo Victoria Theater, where it is second only to "Cats" as the longest-running musical in British history.

The point, Lloyd Webber said, is that "no show is the same animal: `Cats' and `Phantom' and `Les Mis' are not the same" as his shorter-lived "Aspects of Love," a London smash and $8 million Broadway flop.

Still, neither man chose to sound defeated, a fact no doubt partly attributable to the fact that any losses must be set against the hundreds of millions of dollars their hits have made and will continue to make.

"I love musicals, as you know," said Lloyd Webber, who is writing a continuation of "Phantom" set in New York in 1907. "They're my life-blood."

His sentiments were echoed by Mackintosh, who is revising "Martin Guerre" for a new, pared-down regional and touring production to open outside London in November. Beyond that, he has various small-scale shows on target for separate American openings, starting with "The Fix" at Signature Theater in Washington, D.C., opening March 30.

Later in the year, he will bring the Kipling musical "Just So" to the Goodspeed Opera House in East Haddam, Conn., and a revised version of the Stephen Sondheim revue "Putting It Together" to the Mark Taper Forum in Los Angeles, starring Carol Burnett.

"I haven't changed `Starlight Express,' " Mackintosh said. "I don't do anything differently now from when I started. I like putting on musicals full stop. That's all I want to do."