The reference K.357 applies to an unfinished sonata in G major composed of an allegro and an andante, for a duration of around 13 minutes.
On May 22 in London, Sotheby's sells an autograph fragment manuscript of this allegro K.357 (497a). This oblong 23 x 32 cm four page document is estimated £ 300K, lot 20.
These pages of three four-staves systems have a characteristic that confirms that Mozart was tempted by the most unusual difficulties : the right hand of the player on the left and the left hand of the player on the right must be crossed. It is supposed that Mozart wanted to play this sonata himself with a lady friend.
Koechel considered for this opus a creation in 1786 but could not inspect the autograph manuscript. Its watermarked paper is positioning it instead between the end of 1787 and 1789.
We do not know the circumstances of this creation. Since its first edition in 1796, 497a is associated with the andante K.357 (500a) but the relationship between these two movements has been refuted.
SOLD for £ 345K including premium