Cover image not available
pt. 1. The early [locomotive] years
pt. 2. The later steam years + scale drawing of Penthyn Quarry.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
The Penrhyn quarry railways in 16mm scale by Bernard W. Rockett. ISBN 9780956066565. Published by Theodore Press in 2012. Publication and catalogue information, links to buy online and reader comments.