How does a British mathematics professor at Cambridge University become internationally renowned and respected as a Mozart scholar? “Rather by chance,” says Richard Maunder, who’s in Chicago this week in connection with the local premiere of his new edition of Mozart’s unfinished C Minor Mass (K. 427, the “Great”).

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Maunder has long been fascinated by the problems of Mozart’s last work, the Requiem (K. 626), which was incomplete and shrouded in mystery at the time of his death. The Requiem had been commissioned anonymously by the eccentric Count Walsegg (hence the famous “gray messenger”–Walsegg’s attorney), who fancied himself a composer and who routinely hired “ghost” composers to write music that he would pass off as his own. When Mozart died unexpectedly in the middle of composing the Requiem, his widow, who wanted final payment for the work to be made, enlisted one composer after another to complete the manuscript. None was successful, and with nowhere else to turn, she gave the piece to Franz Xaver Sussmayr, an untalented student of Mozart’s who fabricated the legend about having been at the master’s side for weeks before his death, helping him with the Requiem and learning all of his intentions for its unfinished sections. “It’s all rubbish,” says Maunder. “Mozart couldn’t stand the fellow.”

By fortunate coincidence Cambridge also happens to be home to Academy of Ancient Music founder and conductor Christopher Hogwood. “I suppose we had known each other on and off for a number of years, coming across each other now and then. One day I happened to mention that I was working on a new edition of the Requiem. ‘Oh, that’s interesting,’ he said. ‘We’ve been wondering how to go about doing a version of it without all of those awful Sussmayr additions.’ He carefully looked it over, liked it, performed it a few times, and then recorded it.” That best-selling recording, released by chance at the time of the Amadeus mania, served to make the Maunder edition widely known, respected, and performed.

The concerts are Friday night at 8 at the Cathedral of Saint James, 65 E. Huron, and Sunday at 7:30 at Northwestern University’s Pick-Staiger Concert Hall, 1977 Sheridan, in Evanston. Call 642-1766 for more information.