This piece is Psalm 51, but first set to music by Allegri around 1630. It is one of the finest and most popular examples of renaissance polyphony.

It is often heard in Churches of the apostolic Christian tradition on Ash Wednesday, immediately following Shrove (pancake) Tuesday, marking Christ's return to Jerusalem.

Beautifully performed here by The Sixteen, listen out for the simplicity, humility and reverence.