North Wales Narrow Gauge Railways
From Festipedia, hosted by the FR Heritage Group
This was the original precursor to the Welsh Highland Railway.
Formed to be part of a major network of narrow gauge railways throughout the North Wales mountains, the NWNGR built only the line from Dinas Junction to Rhyd-Ddu and a branch to quarries above Bryngwyn, to the south of Caernarfon. The lines opened, in stages, over 4 years from 1877. Originally the Bryngwyn line was the mainline. Due to financial difficulties, a receiver was appointed nearly as soon as it opened. The Bryngwyn line closed to passengers in 1913, and was eventually followed by the closure of the rest in 1916; goods traffic was carried on a 'as required basis' until 1922.
Various extensions were planned. The first were in 1885 when an extension to Caernarfon and a zig-zag line to replace the Bryngwyn incline were proposed. Neither was built but the Caernarfon part was resurrected again between 1904 & 1908 and again in 1922. In 1897 approval was given for an extension to Beddgelert. This was eventually started, around 1904 but probably by then as part of the Portmadoc, Beddgelert and South Snowdon Railway with changes on the approach to Beddgelert.
Reference: National Archives document MT 54/160, MT 54/435, MT 54/455, MT6/1367/11, MT 6/972/8
Further information can be found on Barrie Hughes's site here