Blue Heron releases a 5-CD boxed set of world premiere recordings of pre-Reformation English polyphony, from the largest extant source of such music, the Peterhouse Partbooks, which were copied in Oxford for Canterbury Cathedral in 1540 and now reside at Peterhouse, Cambridge. The source had been badly neglected for centuries because of the loss of the tenor partbook, as well as a number of pages from the treble book, sometime in the 17th century. Nick Sandon, who has dedicated much of his professional life to the Peterhouse partbooks, has restored the missing parts. This set, containing nearly five and a half hours of previously 'lost' music, is a must-have for any serious collector of early choral recordings. It includes all the music from the five Peterhouse CDs Blue Heron released between 2010 and 2017, together with a substantial unified booklet containing new and updated notes on the music by Nick Sandon and Scott Metcalfe. Writing in Gramophone, Fabrice Fitch called the fifth CD 'one of the discoveries of the year'; it was selected both as an Editor’s Choice and a Gramophone Critic’s Choice for 2017.