Gentlemen, once again, please," snapped Manhattan choirmaster Gerre Hancock. "Don't sing as if you are reading a recipe for peanut butter cookies." The gentlemen in question—Hancock's 18 boy sopranos (some as young as 10) and the 12 men who augmented them—had only half an hour to warm up for their debut in London's hallowed Westminster Abbey. "I am very hard on them," admits Hancock. "I know I am out of step with the times. But I feel I have failed unless I demand their very best."

Hancock was concerned over how Old Country Anglicans would react to an American group from St. Thomas Episcopal Church and its choir school. "I am not interested in hearing people say, 'Those nice little kids, aren't they cute.' We were there to sing." Sing they did—standing in their scarlet choir robes on the chancel steps before Westminster Abbey's high altar. As The Times of London noted later with approval: "An American choir bringing the English cathedral repertory to this country must feel like an English singer taking Wagner to Bayreuth. However, the St. Thomas choir can brave competition with the best."

One reason is the stringent admission requirements. Three boys audition for every place at 61-year-old St. Thomas, which is the only church-related choir boarding school for boys in the U.S. It runs from fifth to eighth grade and, with its incredibly high faculty ratio (10 teachers for 41 students), costs $2,750 a year. Hancock, 46, who is a prominent organist as well as choir leader, drives the boys through 12 hours of rehearsals a week. In the process he has made the school preeminent in the field of church music. Their singing at a Benjamin Britten memorial concert in New York last year prompted an invitation from tenor Sir Peter Pears to sing this summer at Britain's Aldeburgh Festival. Hancock booked seven other performances, and the choir's first overseas tour provided a 12-day excursion following its usual two-week summer encampment at Ivoryton, Conn.

"Each boy gives us an indescribably beautiful gift—his voice," says Hancock of his charges, whom he drills in unaccompanied, or a cappella, song. "Hopefully, we give him an appreciation of the thrill of making and hearing music." With the younger boys, influenced by listening to overamplified rock groups, Hancock tones down their delivery. With the older ones he is alert for signs of voice change. "High C's and a mustache don't mix," laments Hancock. "When that dreaded fuzz sprouts, there goes all that wonderful literature we have worked so hard to teach them—gone, all gone."

Hancock saw his own voice change in Lubbock, Texas, where his father was a school curriculum supervisor and his mother a part-time piano teacher. At 5 he started piano lessons and at 10 heard his first pipe organ in a Dallas church. "I said to myself, 'That is it. I have got to be able to do that someday.' " He majored in music at the University of Texas and studied on a fellowship in Paris under French composer Jean Langlais. There he also learned the art of improvisation—a technique he now teaches organ students at Yale and Juilliard—from the famed Nadia Boulanger. "She terrified me," he remembers, "but I knew she loved me."

Gerre met his wife, Judith Eckerman, also an organist, in 1959 at Union Theological Seminary in New York, where they were both studying for their master of sacred music degrees. He moved to Cincinnati as organist and choirmaster for Christ Church and in 1964, while visiting Cambridge, heard the famed King's College choir singing Herbert Howell's Magnificat. "The sound was absolutely breathtaking, unearthly," recalls Hancock. "That was the other turning point in my life. I had to try to build a choral sound like that."

With St. Thomas he has succeeded, but the high-strung, intense Hancock suffered coronary problems that required double-bypass surgery in 1977. The task-and choirmaster has mellowed of late, though. In 1975 he had refused to allow the choir, which has cut several albums (royalties go to the. scholarship fund), to record with a then fledgling rock group. "None of us knew who they were," admits Hancock, adding with a twinkle, "We may have been foolish to turn them down." The group was Kiss.