Mozart's Twelfth Mass (K. Anh. 232) was a bestseller in the 1800s in both Britain and the United States, and undoubtedly helped in the popularisation of Mozart's works among the general public. However, it is now widely accepted that the mass was not, in fact, written by the great Maestro, leading to its rejection by many professional performers. It has, however, remained popular with many amateur choral societies on both sides of the Atlantic.
The Gloria is the only part of the mass that might have actually been written by Mozart. It has been arranged for Male Voice Choir (TTBB) with Organ or Piano by Percy E Fletcher, with English translation by J. S. Stallybrass.