Hancock was a self-controlled young man, apparently immune to the hysteria found in opera houses at moments of crisis. Sir Thomas Beecham, when meeting him before the rehearsals of Die Meistersinger at Covent Garden, asked: "Does he breathe?" Later, Hancock moved to Sadler's Wells Opera (now English National Opera), and then to Scottish Opera, where he became Head of Music Staff. He coached students of the Royal Scottish Academy of Music and Drama, for whom he also conducted many performances. He made several excellent English translations of opera libretti.
Hancock was born in Liverpool in 1921 and studied at Cambridge University and the Royal College of Music. On graduating he joined the music staff of the newly formed Covent Garden Opera Company (now the Royal Opera). It was apparently Vaughan Williams himself who asked for Hancock to conduct the premiere of The Pilgrim's Progress on 26 April 1951; among the cast was the soprano Iris Kells, at that time Hancock's wife. There were seven performances that season and three the following one; the work was judged undramatic, and it was not until 1998, when the Royal Opera gave some performances of The Pilgrim's Progress at the Barbican Hall, that the public changed its mind.
Hancock transferred to Sadler's Wells, where he became chief repetiteur and was given much more scope for conducting. In 1962, for instance, he conducted Carmen, and the following year Cosi fan tutte, in which the soprano Catherine Wilson, who later became his second wife, sang Fiordiligi.
Hancock and Wilson in 1966 moved to Scottish Opera. The company, only four years old, was embarking on a successful period in its history. In 1968 Hancock conducted The Marriage of Figaro. During the next decade at Scottish Opera he also conducted Cosi fan tutte and The Magic Flute; Britten's Albert Herring and The Turn of the Screw; Verdi's La traviata and Falstaff; and two modern operas, Robin Orr's Full Circle (1969), and The Catiline Conspiracy (1974) by Iain Hamilton.
In 1975 Hancock, together with David Pountney, provided a new translation of Die Fledermaus. Pountney directed Strauss's classic operetta, in which Wilson sang Rosalinde. This splendid translation was later used by English and Welsh National Operas. The following year Hancock both translated and conducted Nicolai's Merry Wives of Windsor at the Wexford Festival. Other translations included Gounod's Faust, Un ballo in maschera, and (with Pountney) The Bartered Bride for ENO.
Meanwhile Hancock was regularly conducting student performances, all of a very high standard, for the Royal Scottish Academy of Music and Drama: Britten's The Rape of Lucretia in 1983; The Tales of Hoffmann in 1984; a mixed programme that included Act 2 of Madama Butterfly in 1985; a double bill consisting of Milhaud's Le Pauvre matelot and Purcell's Dido and Aeneas in 1986; and Puccini's Gianni Schicchi in 1987.
Other organisations for young professional signers with which Hancock and Wilson were involved were Clonter Farm Opera in Cheshire, and the William Walton Foundation at La Mortella, on the island of Ischia. In 1992 Clonter staged Cosi fan tutte. That year the Walton Foundation offered Cimarosa's Il matrimonio segreto. In 1993 Clonter and La Mortella both performed scenes from Rossini's La Cenerentola. In 1995 Cosi fan tutte was staged at La Mortella and then, in a truncated version made by Hancock and Wilson, semi-staged at Wexford.
Leonard Hancock, conductor, repetiteur, teacher and translator: born Liverpool 11 September 1921; married first Iris Kells (marriage dissolved 1964), second 1971 Catherine Wilson; died London 17 March 1999.