Spiro began his vocal studies at Trinity College of Music, before continuing on to the Guildhall School of Music and Drama. He has performed Verdi's Macbeth (conducted by Sir Edward Downes), Haydn's Nelson Mass (conducted by Sir Charles Mackerras), Handel's Messiah, Harvey's Passion and Resurrection, Menotti's The Saint of Bleeker Street, Handel's Semele and Janacek's The Cunning Little Vixen (British Youth Opera), Verdi's Macbeth, Bellini's La Sonnambula, and Donizetti's L'elisir d'amore (Opera Holland Park), The Merry Wives of Windsor and The Elixir of Love (Opera South), Der Stein der Weisen (Garsington Opera), The Marriage of Figaro (both for St John's Opera and the Longborough Festival), Death in Venice (Aldeburgh and Bregenz Festivals), Playing Away and Tosca (Bregenz Festival), Carmen (Opera Project), and La Boheme (Longborough Festival). His roles include Antonio and understudy for Bartolo (The Marriage of Figaro), 2nd Gondolier (Death in Venice), Minder and Journalist (Playing Away), and Zuniga (Carmen).

He has given recitals in London, Surrey, and Kent and has also taken part in master-classes with Susan McCullock, Adrian Thompson, Henry Herford and Robin Bowman, and was a founding member of the choral group, Carolus Rex, which has performed at the Painted Chapel in Greenwich, the Greenwich Festival, and at St. James's Palace. He has also performed a solo recital of Scottish Songs at the Lion Ballroom in Herefordshire, a series of concerts as a guest of Swan Hellenic, and, as part of a quartet, a selection of carols in the Floral Hall of the Royal Opera House.

Furthermore, as part of the Britten Festival Chorus, he sang on the new James Bond film, 'Quantum of Solace'.