Incorporated on 14 July 1864. Financial difficulties led to the L&NWR buying 4.5 miles at the Llanberis end with running powers over the rest in return for letting the company use the L&NWR station at Caernarfon. On 13 December 1866, Agreement was reached for joint ownership of the whole line, with L&NWR working it. It opened on 1 July 1869 and was vested wholly in the L&NWR by an Act of 4 July 1870 to take effect within 12 months.