The discovery is believed to be a manuscript copied by someone else of Mozart's original composition.

The original manuscript of Mozart’s Clarinet Concerto was lost ... Jack Brymer’s recording with the London Symphony Orchestra (in which he was principal clarinet) is hard to beat.

And that makes it contemporary to Mozart’s time.” The piece came from the workshop of Johannes Traeg, he added. “The question is, did Traeg work directly for Mozart, or did Traeg get the manuscript ..