So when I got home I looked out the book we have on the Silent Valley, and it is indeed "The Dam Builders - The story of the men who built the Silent Valley Reservoir" by W. H. Carson. It was first published in 1981 by Mourne Observer Press, Newcastle, Co. Down and my dad has inscribed the inside cover with his name and the date August 1983. That was the year I was born incidently. Thought I would post a small excerpt from the inside sleeve:
The construction of the Silent Valley reservoir in the Mourne Mountains of County Down is acknowledged by civil engineers throughout the British Isles and abroad to be one of the most remarkable achievements in the history of dam building.
Before the first sod was cut by Lord Carson of Duncairn on 10th October, 1923 a 22 mile long wall of rough granite slabs was cut by hand across the mountains to enclose the catchment area. Some of the stone-men who toiled for 18 years on this back-breaking job went on to work in the Valley when the wall was finished, and it is the strength of the author's research that he suceeded in tracking down and talking to four of the original mountain wall builders, and 36 of the men who worked on the construction of the reservoir.
Interspersed with fascinating character studies of leading personaliies, and illustrated with a wealth of historic and contemporary photographs, the human story of the men who built the Silent Valley reservoir moves in step with the history of events in the Valley recorded between the years 1923 and 1933.
Indeed, the first chapter of the book is entitled "The building of the mountain wall". In an appendix there is also a "Roll of the Mourne Wall Builders" with names of men known to have built the Mourne Wall. There are two Patterson's on the list which I believe are related. Will have to find out more.
Here is a photo of the jacket sleeve for those interested:
(http://i162.photobucket.com/albums/t253/suspectmonkey/Other/Dam_Builders_Cover.jpg)