This is a reconstruction of Mozart's 1781 draft for a horn concerto in Eb, comprising K.370b and K371, most probably intended for the first series of Vienna concerts the composer had planned. The style is different from those written for Leutgeb and may have been intended for the Munich player who featured in Idomeneo. There are two movements, the first of which was cut up into fragments by Mozart's son Karl to give away as souvenirs. These have now almost all been rediscovered except for about eight bars. The second movement reinstates the fifty missing bars of the Rondeau in Eb. Both movements were written on the same watermarked paper of 1781.

This reconstruction has been recorded by Roger Montgomery and the Orchestra of the Age of Enlightenment and featured as a news item on various media. It has received critical acclaim from, amongst others, The Times, The Gramophone, The Birmingham Post and the BBC.