On Saturday night, a large and diverse audience gathered in Leeds Town Hall to hear Leeds Festival Chorus and the Northern Sinfonia perform an all-Mozart programme, which provided an appropriate and atmospheric end to the composer's birthday week. The evening began with the Symphony No.40 in G Minor. Conducted by Simon Wright, the ever-popular piece made for an energetic start to the evening, and showcased what a perfect fit the Northern Sinfonia are for Leeds Town Hall.

Then came the main event- the Great Mass in C minor, which, like many Mozart works, is unfinished. A large amount of editorial effort is required to reconstruct parts of the Sanctus, while other elements of the piece, such as the Agnus Dei and most of the Credo, are missing altogether. Despite this, it is a popular and compelling concert piece - dramatic, beautiful and powerful. Unlike a lot of religious works, Mozart didn't write it for commission, but as a personal thanksgiving for his forthcoming marriage. His betrothed, Constanze Weber, was an accomplished singer who performed at the work's première in 1783, and many believe her voice to have influenced Mozart's composition of the two soprano parts which dominate the Mass.

We were treated to two critically acclaimed sopranos, Sophie Bevan and Elizabeth Watts. Bevan has sung the Mass before under the baton of Sir Charles Mackerras and has a voice extremely suited to Mozart. As she sang Laudemus te, I had visions of her maturing into a wonderful Countess Almaviva. Watts, however, was the show-stealer. From the first note of her Kyrie eleison, it was obvious why she has attracted so many prizes and rave reviews. Her voice is creamy yet very pure and lyrical with the capacity to soar over the orchestra in a seemingly effortless fashion and to reach exquisite and powerful top notes. I was astounded by the way she filled the whole of the high-ceilinged auditorium with her wonderful sound, and it was impossible not to compare her projection to the other three soloists, who never quite reached her level. Tenor Nicholas Mulroy is a prolific recitalist, but seemed to lack energy during the Quonium tu solus, and the Mass has such a tiny bass part that bass-baritone Neil Baker sadly didn't have the opportunity to shine.

Shining brightly were Leeds Festival Chorus, who could never be accused of lacking vocal power. In recent years they have been highly praised, particularly for diction and dynamic range, both of which were in evidence on Saturday. Carried away by their beautiful accompaniment to Watts during the Kyrie, I nearly jumped out of my seat when they began the Gloria, so instantaneously huge was their sound. They summoned the same power and beauty for the opening of the Sanctus, and the complex parts which followed were breathtaking. The soloists' quartet which finishes the Mass left me wondering what the response to the work would have been had Mozart completed it, given how emotionally evocative it manages to be in its unfinished state. I left Leeds Town Hall feeling privileged to have heard it performed by the wonderful combination of Leeds Festival Chorus and the Northern Sinfonia, and anticipating their future collaborations with excitement.