As part of his association with BBC NOW, Puw was commissioned by BBC Radio 3 to compose for the 2007 Proms. His orchestral piece, ("... unless I open the door ...") was premiered on 9 August 2007, conducted by David Atherton. It is based on a story from the Mabinogion, a collection of medieval Welsh tales, in which a group of warriors, lately returned from Ireland, feast in Harlech for seven years with the severed head of their leader at the head of the table. They then feast in Penfro for eighty years in a hall with three doors, and only remember the dreadful events that happened in Ireland when the third door opens. Each of the three doors in Penfro was represented by an instrument in a box in the Royal Albert Hall.