Her voice and delivery light and clear, with pinpoint pitch accuracy and minimal, finely controlled vibrato seemed to many musicians and listeners to be an ideal match with old instruments and performing techniques, though that style was not at all in favor in most music colleges and conservatories. When the Academy and the Consort began making recordings for the L'Oiseau-Lyre/Decca label, Kirkby's singing captured the ears and imaginations of a large audience, and she effectively became a standard-bearer for the entire historically-informed performance movement.
During her first heyday in the 1980s, Kirkby's singing was rather violently rejected by some of the mainstream musical establishment, especially in the opera world, and her work remains somewhat controversial among classical vocal fans to this day. On the other hand, she was number ten in a critics' poll of the 20 greatest sopranos of the sound recording era published earlier this year by BBC Music magazine, and she was the only currently active soprano in the top ten (not counting cameo appearances by Montserrat Caball_).
While Kirkby's primary focuses have been on Renaissance song and sacred and secular music of the Baroque era, her repertoire has ranged from the 12th-century abbess Hildegard von Bingen to the early 20th-century American composer Amy Beach. (The Hildegard recording on which she appears, A Feather on the Breath of God by the ensemble Gothic Voices, is by far Hyperion Records' best-selling release and has never been out of print since it was first issued in 1980.)
Her most celebrated recordings, in addition to the Hildegard, are probably of Pergolesi's Stabat Mater (with countertenor James Bowman), Bach's cantata Jauchzet Gott in allen Landen (BWV 51), and Handel's oratorios Messiah, La resurrezione and Athalia. She also made the first recording of Handel's early setting of Gloria in excelsis Deo for soprano and strings which was authenticated in 2001.
Unusually for a soloist of her prominence, Kirkby has remained active in ensemble singing vocal chamber music, in effect throughout her career.
Among other classical musical figures on the 2007 Queen's Birthday Honours list are: dramatic soprano-turned-mezzo Rosalind Plowright and tenor Stuart Burrows, both stalwarts of English National Opera and other British companies, awarded the Order of the British Empire; composer and organist Francis Jackson, longtime organist at York Cathedral, also awarded the OBE; Ruth Nye, renowned piano teacher and professor at the Yehudi Menuhin School and the Royal College of Music, named a Member of the British Empire; and composer Errolyn Wallen, named MBE.