XL is the new choral work by English composer Antony Pitts. It uses the same forces as Tallis' sublime 40 part motet Spem in Alium, and was composed as a companion piece. XL is on a new Harmonia Mundi CD sung by the Rundfunkchor Berlin directed by Simon Halsey. It also includes the Tallis motet, Knut Nystedt's Immortal Bach, and Zoltán Kodaly's substantial Laudes organi.
Other posts linking to the work of Antony Pitts, and well worth reading are Jerry Springer rebel grabs Gramophone accolade and
Raindrops are falling on my chant.