It's quite shocking that, on an all-Mozart program, there could be not one, but two works never before performed in the US. Yet that's the gift that the Philharmonia Baroque orchestra unveiled for the start of its 30th anniversary season. Now, no one found a missing symphony in a trunk in a Salzburg attic. The "new" piece is a re-creation of a concerto movement that the young Mozart, age seven, composed and whose piano part, and only the piano part, his dad confined to a music book for Wolfgang Amadeus's sister Nannerl.
Robert Levin, a Mozart scholar, Harvard music professor and fortepiano concert performer, wrote up with the proper respect the string orchestration to go along. Another prelude in the same book was missing its second half, Levin made it whole. Ta-da, two new Mozart pieces. Which he performed last night with the period orchestra conducted by Nicholas McGegan. And it sounded just like Mozart, joyous and inventive and unpredictable.