The Little Sweep has likely been performed more often than any other opera by Benjamin Britten. It is the second part and realization of Let's Make an Opera, an "Entertainment for Young People." Its didactic purpose is to acquaint children (and others) with elements and conventions of opera. Stephen Arthur Allen has also pointed out an additional, more subtle function: showing them the "subversive and powerful irony to which the genre is capable."
In essence, The Little Sweep is a rescue opera, in which children, aided by a very sympathetic nursery maid, liberate a nine-year-old apprentice chimney sweep from his cruel master and dangerous trade. As in many of the composer's works, betrayal of innocence is an important theme. While they were working together on Albert Herring, Britten and librettist Eric Crozier had discussed writing an opera for children, the result of which was The Little Sweep. There are obvious parallels to Charles Kingley's popular book The Water Babies well-known to Britten, who, as a child, had performed in a dramatic adaptation of the work. The fundamental inspiration, however, came from William Blake's poem "The Chimney Sweeper," which the composer was to later set in Songs and Proverbs of William Blake.
Musically, The Little Sweep finely demonstrates Britten's skill in writing accessible, non-patronizing music for children and amateurs. It is also a prime example of how cleverly he could deal with serious matters without being obvious or ponderous.
Employing smaller instrumental forces than in any of his previous operas, The Little Sweep calls for string quartet, piano duet, and percussion. Four professional adult singers are needed; the rest of the roles are for children. Some have complained of the use of spoken dialogue and the paucity of solo songs/arias. As well, mention is made of the risk of giving the audience such a vital part and challenging music to sing.
The four audience songs are amongst the most interesting parts of the opera. Success with the audience hymns in the cantata Saint Nicolas (1948), which easily allowed the audience to participate in the performance and comment upon the story, emboldened Britten to provide more challenging material, given the chance for rehearsal, in The Little Sweep. In these participation pieces the audience is a sort of Greek chorus, involving them in the action and on a deeper emotional level. Audience members are asked to sing dissonant harmonic intervals in 5/4 meter as they begin the opera with The Sweep's Song. The second interlude, Night Song, divides the audience into four different parts, representing owls, herons, doves, and chaffinches; this latter group is even called upon to sing high Gs rhythmically in falsetto!
Let's Make an Opera was first performed at the 1949 Aldeburgh Festival. Britten's trusted amanuensis, Imogen Holst, wrote that the audience songs "caused a hubbub of excited comment at the first performance, when hardened opera goers anxiously clutched their song sheets."