When we think of an unfinished masterpiece by Mozart, thoughts naturally go straight to his final work, the Requiem, the story of which has been greatly romanticised on stage and screen, or perhaps the Great Mass in C minor. A closer look at the Köchel catalogue reveals a number of other unfinished works, including Thursday evening’s opera L’oca del Cairo, an Italian opera abandoned by Mozart in 1783, just a few years before his famous collaborations with Da Ponte.

Frustrated by the theatrical naivety of librettist Varesco, and tempted by offers of better commissions, Mozart wrote to his father in early 1784 to say that the music he had written so far had “been put away safely”. He was never to return to the piece, but what remains are detailed sketches of most of Act I, including several arias, duets and trios and a complex finale.

The work has appeared in a number of guises over the years, with the majority of interpretations presenting the work as unfinished, whether that be with a faithful orchestration of Mozart’s sketches or, as with the 2006 Salzburg production, an almost exact reading of Mozart’s score. In a bold artistic move, as part of their Mozart Explored: 1783 series, the London Mozart Players, under the baton of David Parry, decided to give the UK première of Stephen Oliver’s 1991 completion of the opera, originally staged at the Batignano Festival to mark the bicentenary of Mozart’s death.

Wisely, Oliver chose to avoid any pastiche of Mozart’s idiom and instead wove his wove modern compositional style, at times reminiscent of Thomas Adès, into the original music to present a complete 90 minute work. Mozart’s original music was orchestrated with care and divided across the entire work, allowing both acts to end with sparkling Mozartian finale. The story is largely a realisation of Varesco’s original plot, borrowed itself from a classic renaissance story. Two maidens are imprisoned in a tower by a lonely and cunning collector of fine objects who hopes to make one of them his wife. Two resourceful suitors manage to set the girls free with the aid of a giant mechanical goose and some assistant from their captor’s long-estranged wife.

The London Mozart Players and David Parry showed great skill in navigating these two opposing idioms and playing styles, producing a sparkling and light effect in Mozart’s passages and then dealing with the rhythmic and technical challenges of Oliver’s modern score. The soloists for the most part showed tremendous skill. Alexander Robin Baker was a dynamic and imposing stage presence with an incredibly rich, yet nimble voice. Christopher Diffey rose to some amusing challenges posed by Oliver’s vocal writing, including the requirement to hold some notes for a seemingly inhumane amount of time. Soraya Mafi and Fflur Wyn also shone as the two maidens imprisoned in the tour by the elderly and foolish Don Pippo.

There were moments when the shift from Mozart’s to Oliver’s writing felt unnatural, occasionally a Mozart aria would be attacked with the same concentration and attack as the complex, modern sections, which removed the sense of effortless and grace normally associated with Mozart’s operatic writing.

Overall the evening was a success, and the performance was both musically and theatrically captivating regardless of the lack of staging. There were many moments, particularly in the finales to both acts, that easily called to mind Don Giovanni and Le nozze di Figaro, and we can only imagine, with the help of a more organised librettist, what Mozart himself might have had in mind for Act II.