[1] Cantelo made her solo debut in 1950, with the Glyndebourne Company at the Edinburgh Festival as Echo in Ariadne auf Naxos by Richard Strauss, then also Barbarina in Mozart's Le nozze di Figaro.

[1][4] She performed at the Glyndebourne Festival the following year as Barbarina, and in 1953 as Echo and as Blonde in Mozart's Die Entführung aus dem Serail,[1] and again in 1963 as Marzelline in Beethoven's Fidelio.

[1][5] In the first half of the 1950s she appeared at the Royal Opera House, in a small role in Mozart's The Marriage of Figaro,[1] as Barbarina, Countess Ceprano in Verdi's Rigoletto and as Poussette in Massenet's Manon.

Cantelo performed in the British premieres of Hans Werner Henze's Boulevard Solitude (as Manon Lescaut) in 1962 and of Kurt Weill's Rise and Fall of the City of Mahagonny (as Jenny) at the Sadler's Wells Opera in 1963.

[1][2] In 1979, Cantelo and the conductor Roger Smith founded the Highnam Court Project, to restore a 17th-century mansion which had belonged to Hubert Parry's family, and use it for a foundation for the arts.

[1] Grove describes her voice as "a pure, clear lyrical soprano, not large, but capable of flexibility and variety of expression", calling her "a very gifted singing actress".

She trained an amateur choir, All Saints Singers at Sutton Courtenay, and invited former colleagues to sing solos in Masses by Haydn, Bach's Passions and oratorios by Telemann.

[12] She recorded a solo recital program of 14 songs from the eighteenth century by various composers, all using lyrics by Shakespeare, with Raymond Leppard conducting the English Chamber Orchestra (L'oiseau-Lyre).

[8] In classical and romantic music, she sang Servilia in the English-language performance of Mozart's La clemenza di Tito under John Pritchard, deputising for the indisposed Jennifer Vyvyan (Nimbus Prima Voce).

She recorded part songs by Schubert (Argo, 1967),[12] the roles of Candida and Bettina in Donizetti's Emilia di Liverpool alongside Joan Sutherland (BBC/Myto), Héro in Béatrice et Bénédict by Berlioz,[2] conducted by Colin Davis,[11] and mélodies by him (Philips), Celia in Sullivan's Iolanthe under Sir Malcolm Sargent (HMV), and Solveig songs from Grieg's Peer Gynt with the Royal Philharmonic Orchestra under Alexander Gibson (World Record Club).