Part of the BBC Proms.Begun to celebrate his marriage to Constanze, but left unfinished at the composer’s death, Mozart’s magnificent Mass in C minor can clearly be traced back to the choral writing of J. S. Bach and his son. Period-performance specialist John Butt and the award-winning Dunedin Consort unpack the Mass’s musical genealogy, with soloists including Lucy Crowe and Nardus Williams.