It looks like something Jake and Dinos Chapman might do if they turned their hand to the creative defacement of illuminated manuscripts: the Viz-style gargoyle just to the left of the plainchant notation on page 77 of the nearly 700-year-old Bangor Pontifical, one of the treasures of the Welsh medieval world. On a road trip through the country to create a Welsh Christmas for this Saturday’s Music Matters, I saw, handled and turned the pages of this book at Bangor University. The Pontifical is one of the fountainheads of Welsh music history because nearly two-thirds of the manuscript contains musical notation as part of the services the bishop would conduct – including a handful of chants, such as In civitate domini, that are found nowhere else in the world.