Giovanni Pacini might be the most prolific opera composer you've never heard of. His 70-plus stage works have slipped into the kind of obscurity from which only the recording company Opera Rara and its annual concerts can rescue them. Premiered in 1824, Alessandro nell'Indie was the first of many works Pacini wrote for the operatic hothouse that was Naples. He was very much in Rossini's shadow; swaths of music go by without offering much to grab the attention of anyone but connoisseurs of 19th-century opera. But it's those connoisseurs Opera Rara caters for, and they were out in force for this concert.

A strong international vocal lineup was headed by Bruce Ford's resonant Alexander the Great; however, the star was Jennifer Larmore, her mezzo sounding firm but pliant in the Indian king Poro's demanding vocal fireworks.

Pacini rarely allows the music to stop, which ought to mean that the drama flows, but it doesn't; he takes a long time to tell a short story. Yet there are highlights, and, perhaps surprisingly for such a showcase of vocal athleticism, they come at more reflective moments, such as Cleofide's grief-stricken aria, sung by soprano Laura Claycomb with solo cello, and the harp-accompanied quintet near the end.

David Parry conducted the London Philharmonic efficiently, and the chorus of soldiers, lost at the back of the stage, will no doubt sound less wimpy on the forthcoming recording. But some composers are made for highlights discs; Pacini Rediscovered, already available, is probably a better bet.