Allegro
Adagio
Rondeau. Allegro 

String Duo No.1 for G major and its companion String Duo No.2 in B-flat major were not originally credited as being Mozart’s works. In 1783, Mozart’s friend Michael Haydn – a fellow composer and younger brother of Joseph Haydn – had been tasked with writing six duos for the Prince-Archbishop Colloredo, who employed both Michael Haydn and Mozart. Haydn fell ill before he could complete all six of them, and as a favour to his friend, Mozart completed the set with String Duos No.1 and No.2. Colloredo was none the wiser that two of the pieces hadn’t been written by Haydn, and it wasn’t until a subsequent newspaper advertisement went out that anyone realised Mozart was responsible for them. 

String Duo No.1 differs significantly from its counterpart due to the fact the viola has a much more complex and conversational role, as opposed to being just an accompaniment for the violin. The first movement of the duo is an Allegro, containing an expressive conversation between the two instruments. Each theme is passed back and forth, extending the development section until it almost runs away with itself before impressively reigning itself in for a comparatively subdued ending. The Adagio in contrast is extremely peaceful, with the melody and the harmonic support tenderly balancing each other out. The final Rondeau returns with the vigour of the opening movement, rounding off the lyrical conversation with vitality and Mozart’s trademark wit.