the end authors note most of the details about the building of the dam and the flooding of the valley are accurate , but sometimes the sequence of events has been altered for narrative purposes acknowledgements my thanks go to liverpool reference library ; the powys archives at llandrindod wells ; gladys mary coles , poet , biographer and lecturer ( for her encouraging response to the early chapters ) ; meirion edwards , lecturer in welsh ( for checking my use of welsh and making useful suggestions ; john heap for his help with preparing the manuscript for publication .