It was later operated by the LNWR then the LMS. At Afon Wen, a junction connected with the Cambrian Line (GWR) to Pwllheli in one direction and to Porthmadog in the other, with LNWR/LMS running rights to both. The line had two branches, one from Caernarfon to Llanberis, which was built by the Carnarvon and Llanberis Railway and the other from Penygroes to Nantlle, which formed part of the narrow gauge Nantlle Railway, which between Penygroes and Caernarvon had been incorporated into the Carnarvonshire Railway.
Regular passenger service on the Llanberis branch ceased in the 1930 (but summer passenger excursions from Llandudno etc. ran from 1932 until 1939 and again from 1946 until 1962). Likewise the Nantlle branch passenger service also ceased in 1932. The remaining lines and services (Afon Wen to Caernarvon) were shut completely as part of the Beeching Axe in December 1964.
A section of the line, from Caernarvon to Dinas, was incorporated into the reopened narrow gauge Welsh Highland Railway as the first phase of the line, in 1997. Several miles of the trackbed southwards from Dinas have been used to improve the A487 road. Some original sections remain and have been used as part of National Cycle Route 8.
The tunnel under the centre of Caernarfon has been reopened for road traffic.
- Awdry (1990)
- Awdry, Christopher (1990). Encyclopaedia of British Railway Companies. Sparkford: Patrick Stephens Ltd. ISBN 1-8526-0049-7. OCLC 19514063.
- Jowett, Alan (March 1989). Jowett's Railway Atlas of Great Britain and Ireland: From Pre-Grouping to the Present Day (1st ed.). Sparkford: Patrick Stephens Ltd. ISBN 1-8526-0086-1. OCLC 22311137.