She’s still an angel, but at 15 Charlotte Church looks more like a messenger from Rubens than from Botticelli. No complaints — she’s grown into an attractive young lady. But the voice that enchanted thousands of PBS viewers hasn’t grown with her — as was painfully obvious at the Wang Theatre on May Eve.

Wearing a backless glittery top and long satiny skirt, and with her hair in a ponytail, Church appeared briefly at 8 to offer giddy greetings and ask us to put our hands together for flamenco guitarist Jesse Cook. At 8:45, after her 50-piece “Fantastic Boston Orchestra” had slithered through a West Side Story medley, she returned to sing “Tonight” and “Somewhere,” then “Panis Angelicus” and, from Carousel, “If I Loved You.” She waved goodbye and it was intermission, time to stand three deep at the Wang boutique and hope to snap up a Charlotte Church T-shirt ($25) or mousepad ($15) or autographed photo ($10). Few in the well-filled theater ($76 for all the floor seats and a good part of the balcony) seemed to mind that her voice is breathy and not always certain of pitch, that at the top it becomes painfully shrill, that her diction is all over the place, or that she can’t phrase.

The Fantastic Boston Orchestra opened the second half with a rendition of the Overture to The Marriage of Figaro that made me wish I were at the Pops. Charlotte came on in periwinkle blue and did a harp-accompanied Welsh number whose title not even this reporter’s doctorate in Celtic languages enabled him to make out (the $76 notwithstanding, this was a no-program event) and then an Irish one, “My Lagan Love.” She showed off her coloratura in “La Pastorella,” but there was no color in her voice for “Pie Jesu.” Another orchestra break: the Intermezzo from Cavalleria rusticana, with the strings abysmally flat, and the Overture from Carmen.

Charlotte back in a glittery gold top and red skirt for “A Bit of Earth,” from The Secret Garden. “Thank you for being such a great country!” Her second-favorite song: “Bali Ha’i,” from South Pacific, its lower range and Bloody Mary’s broken English both a plus for her. Then, a song that she admitted calls for experience and the wisdom of age, but, “Sorry, critics, but I really love this and I really want to sing it.” Brünnhilde’s Immolation? “The House of the Rising Sun”? Nope, “Bridge over Troubled Waters.” The voice had by now warmed up a bit, and she showed a budding maturity. The first encore was her very very favorite song, “Summertime.” And just one more (“I gotta go home, gotta go to sleep, I’m only 15”), with the harp again, “Danny Boy.”

It’s not that the vocal talent isn’t there, and Charlotte has a direct, appealing personality. But what was cute at age 12 is less so at 15 and won’t work at all when she’s 20. She needs a real vocal coach, someone who can develop that voice, tell her what’s appropriate for it, teach her how to enunciate and how to phrase, maybe even how to dress. And her family need to let her grow up. Then she’d be an artist. Otherwise, she’ll wind up with the likes of André Rieu and Helmut Lotti as just another PBS commodity.