THE father and son team who broke historic Rosslyn Chapel’s musical Da Vinci Code have done it again with another of the artist’s riddles. Stuart and Tommy Mitchell believe they have cracked another secret of the Renaissance genius, this time in Leonardo’s famous portrait The Musician. Art historians have remained baffled for centuries over the meaning of the work.They have also puzzled over the writing on the piece of music held by the subject of the 1490 painting, believed to be Da Vinci’s great friend Franchino Gaffurio. Now Stuart and Tommy have used mirrors to reveal the words “agnus dei” and a musical score. Once the score is fully deciphered, Stuart plans to incorporate it in one of his classical pieces.as he did with the notes he found in Rosslyn.