In 1845 Franz Liszt embarked on a project to compose an Italian opera based on Lord Byron’s tragedy, Sardanapalus (1821). It was central to his ambition to attain status as a major European composer, with premieres variously planned for Milan, Vienna, Paris and London. But he abandoned it half way through, and the music he completed has lain silently for 170 years.

Liszt’s difficulty in obtaining a libretto meant that composition only began in April 1850. He completed virtually all the musi...