The tune starts in Llanyblodwel, listening to the silence that is the river’s timeless backdrop. As we travel up the valley the hills rise in tumbling folds, their sharply detailed forms animated by a spectral light. Narrow here, widening out there, they suddenly narrow then rise and rise again.

And now, they are massive looming forms, towering above as we approach the foot of the Berwyns at Llangynog. To the left is the winding valley of Cwm Pennant, and the river’s source.