The main line of the Saundersfoot Railway (nprn 43052) opened in 1832 between Saundersfoot Harbour (nprn 34611) and Thomas Chapel. It was built to a gauge of 4ft 0 3/8in and originally worked by horses. King's Moor Tunnel carried the line under rising ground below the hamlet of Hill and the site of the 1866 Saundersfoot Station on the Whitland extension of the former Pembroke & Tenby Railway. The tunnel is 450m long, 2.44m wide and approximately 2.6m high with a semi-circular arch.
Sources include: The Saundersfoot Railway, M R C Price, Oakwood Press, 3rd edition 1978.
B.A.Malaws, RCAHMW, 18 September 2013.