The Secret Arias, Opera House, Copenhagen

The Secret Songs is, in reality, a snapshot of a work in progress, with the finished opera not scheduled for performance until the spring of 2007. What Costello presents is a 70-minute song cycle with 10 numbers that will form the backbone of the full-length piece.

Costello discovered classical music in the late Eighties, and has been a regular listener and writer for the genre since, including notable collaborations with the Brodsky Quartet, Anne Sophie von Otter and, most recently, a ballet score. With Andersen, he has a wealth of material to play with and he's latched on to the relationship with Jenny Lind, the Swedish Soprano, who, for a brief time, was the subject of his unrequited affections. They shared a similarly impoverished background and had a talent that projected them on to a world stage. Costello's story centres on her famous tour to the US, masterminded by the impresario P T Barnum, with Andersen musing on her endeavours and writing secret songs that he hopes she will sing, and reflecting, on his death bed, about his nightingale.

The work was partially staged with giant captions denoting time and place accompanying grainy projected images, but Costello doesn't go much for on-stage characterisation in the his roles: it's Barnum with top hat, and Andersen without, and it's left to Swedish soprano Gisela Stille, in the part of Lind, to do the acting. Vocally, Costello has tried to develop a different musical thread for all three parts, but the ear-catching music comes in the more operatic numbers he has written for Lind, requiring Stille to use her classical technique to carry them off, thankfully without mic. And in "He Has Forgotten Me Completely", a haunting piece sung with style, and with a hallmark Costello continuo of keyboards and cello, he has a cracker.

Costello's libretto is beautifully crafted and intense, and the work, performed in English, is one that bears study. Asked if it had whetted his appetite to write more opera, he was typically candid: "It's whetted my appetite to write this one." The Secret Songs is no ugly duckling, but only time will tell if it will develop into a beautiful swan.