HARD LOBBYING IN THE THEATER : If You Can’t Take Show Home, Just Buy a Souvenir or Two or . . .

The first-act curtain came down, and the audience rushed out of the auditorium. They pushed and they shoved. They packed the lobby so tight you could only move if the person in front of you moved.

Forget the bar and the bathrooms. This crowd knew its priorities. These people had only 15 minutes to shop.

I was at “The Phantom of the Opera,” the new Andrew Lloyd Webber musical. Assuming I was in line for the ladies’ room, or maybe the bar, I held my ground. And it was only with fierce determination that I managed to slip out of line without buying a single sweat shirt, mug or watch. (The show opened in October and recordings weren’t out yet.)

The “Phantom” phenomenon haunted me through two weeks worth of theatergoing. Wherever I went, crowds packed around the sales counters, and frantic ushers had to pry people away to get them back for the second act.

Loaded with hit musicals, the West End has become shopper’s heaven. Forget Harrods and Liberty. Who cares anymore about Oxford Street and King’s Road? Tourists wander the Strand and the Haymarket lugging plastic bags with “Chess,” “Starlight Express” and “Les Miserables” logos.

At first, I resisted. But then I surveyed the larger picture: Could thousands of other American visitors be wrong?

By my third musical, I was unquenchable. I leaped in the air to catch the tacky “Chess” Frisbee someone threw from the stage (and, later, wrinkled plenty of clothes wedging it into my suitcase). When the first act ended at “Chess,” I not only raced into line but bought everything that didn’t move first. Even at the serene Royal Shakespeare Company stages in Stratford, I rushed out at intermission with my hands full of money.

It’s the theatrical version of the museum gift shop. More and more museums here as elsewhere sport thriving, crowded gift shops. The National Gallery has even started selling frames to show off postcards of artworks.

Culture travels. If you can’t take home the show, bundle up a souvenir. Recordings obviously remind us of the shows we enjoyed, and the T-shirts keep us warm while we’re listening. Colorful programs depict scenes for friends back home who can’t understand how somebody could pull off a musical about a U.S.-Soviet chess match, much less Victor Hugo’s monumental novel.

The sales opportunities seem endless: One theater here peddled dried edelweiss during a run of “The Sound of Music.”

Remember all the items they have hawked at “Cats”--the shopping bags, the “Memory” sheet music, the copies of T. S. Eliot’s “Old Possum’s Book of Practical Cats?” One saleslady told me half the audience usually bought something before the show. And the other half, she quipped, bought on their way out.

(She may be right. When “Cats” composer Webber took his Really Useful Group company public a year ago, the prospectus noted among other things that the merchandising of clothing, records, cassettes, souvenir brochures and gifts rang up 348,000--about $522,000--in the prior fiscal year alone. And Webber currently has three hit musicals on the West End.)

Consider the wares at “Phantom of the Opera.” In the lobby at Her Majesty’s Theatre, the traditional button badges, coasters, and souvenir brochures were just the start. A “See-It Watch” has a magic dial whose image appears and disappears every 30 seconds. A mug’s invisible “Phantom” becomes visible when you add hot liquid, then fades again when the liquid either disappears or gets cold.

An executive at Dewynters Ltd., the advertising company here that designs and markets all these products for theatrical producers, wouldn’t tell me sales figures, but confided that “at least” one in two theatergoers walks out with something. And by the time we finished some coffee--his came in a “Chess” mug, delivered by an assistant in “Cats” T-shirt--he’d convinced me that I, too, had to have a “Phantom” mug.

You can imagine my delight to learn that all those musicals are U.S.-bound. “Starlight Express” opens on Broadway Feb. 26, and “Les Miserables” is currently playing Washington en route to a Broadway opening March 12. “Chess” and “Phantom” are also expected to cross the Atlantic, probably next season.

One colleague, forlorn that on a recent London visit she ran out of money before she could buy a “Les Miserables” T-shirt, has already sent money ahead to friends in New York.