Rhys Mwyn is an entertaining and informative guide to his native patch, which stretches from the top of Snowdon to the seaside resort of Barmouth, from the slate quarries of Llanberis to the exotic village of Portmeirion, and from Prince Charles’ investiture at Caernarfon to the iconic ‘lake’ at Treweryn and Ynys Enlli the island of 20,000 saints.