Handel's "little opera" Acis and Galatea suffers from something of an identity crisis: it exists in three versions, and has also been put forward as a candidate for at least three genres: masque, opera or serenata. It is certainly an unusual piece: small, with a fast-paced but surprisingly simple plot taken from Ovid's Metamorphoses, and voiced by the disconcerting combination of one soprano, three tenors and a bass.

The Academy of Ancient Music chose to perform the original Cannons version, composed by Handel as an entertainment for James Brydges, Earl of Carnavon at Cannons, the Earl's house in Edgware where Handel spent some time as composer-in-residence. Presumably, Handel's peculiar vocal palette for Acis and Galatea reflects the singers available to him at the time in the Earl's household: it produces a unique texture, with sparkling soprano arias and warm unison singing, as well as showcase moments for tenor and bass. Handel's almost extravagantly active writing just goes to show he felt no constraint in terms of musical creativity with such a small and, in some senses, unbalanced team. An affectionate, consciously erudite atmosphere of wit and humour infuses both the music and John Gay's libretto; although it went on to gain significant public popularity, Acis and Galatea feels above all like a drawing room piece, a clever little private joke whose frame of reference is just wide enough to include you too.

From an overture of pulsating energy, we resolved into a lushly pastoral sinfonia in whose chorus Rowan Pierce's clean, fine-toned soprano and Ashley Riches' sumptuous bass could be clearly distinguished. Rowan Pierce went on to shine throughout the night as Galatea, the nymph who sees her beloved Acis killed by the jealous giant Polyphemus, but makes her lover's memory immortal by transforming him into a fountain. Pierce's soaring soprano, embellished here and there with tasteful vibrato, felt perfectly fitted to the space, and might well fill somewhere larger than Cambridge's West Road Theatre in time; while her spry, poised approach to both her character and her music reaped dividends. She was a pleasure to watch and to hear. Concert performances can be difficult to judge right in terms of characterisation and stage business; Pierce's dynamic facial expressions, and understated gestures, got it just right.

Ashley Riches was a delight as Polyphemus, the lovelorn giant whose attempts at poetry and lovemaking are as endearingly hopeless as they are comic. Handel gives Polyphemus some of the most interesting musical tasks in the opera, especially his violent bass incursions into Acis and Galatea's swooning love duets, which eventually culminate in more than musical aggression, with Polyphemus hurling the rock which kills Acis. Riches' strong dramatic instincts and penetrating dark notes made for an entertaining, and ultimately moving, portrayal.

Andrew Tortise did not have quite such a fun role, nor quite so much success, with Acis, the stock-issue shepherd lover; Acis doesn't have much to do other than love Galatea, then die, but Tortise's tendency to swallow his consonants sometimes compromised his accuracy, and provoked an occasional tendency to rush his lines. Still, Acis gets some classic Handel melodies to play with, harmonically resolved to mathematical perfection, yet still gently teasing all the way through.

Gwilym Bowen made progress with Damon, initially singing with a nice sense of attack, but a great deal of tension in his back and shoulders which threatened to constrict his voice and left no room for acting. Later, however, Bowen relaxed and opened up into a fine account which showed real promise, with skilful ornamentation to boot: "Wretched lovers" proved a treat. Edmund Hastings produced calm, confident support in chorus moments as Corydon.

The Academy of Ancient Music, conducted from the harpsichord by Richard Egarr (sporting a black silk Oriental jacket, possibly a nod to the orchestra's recent tour of Bangkok), gave a sprightly, pictorial account which encompassed all Handel's charming musical details: bird calls mimicked by sopranino recorder, or cooing doves by the oboe. Handel's score is a mixture of the whimsical, the knowing and the deeply, devilishly clever, with occasional unexpected low notes punctuating the vocal line when you least expect it: the joke, it seems, never quite stops, and even the tragedy of Acis' death only has a glancing effect – enough for one mournful chorus, but no more. Life, ideas and music moves on: the lasting impact is of sophisticated beauty, tinged with humour.