|This article is about 'the South tunnel'. You may be looking for 'the castle tunnel'.|
The railway reached Tidmouth in 1905 by means of a road-side tramway from Knapford; however a gale in the autumn of 1908 destroyed it. In 1910 a treasury grant was obtained and a single tunnel was cut through the ridge south of Tidmouth and laying a railway directly from Tidmouth to Knapford, forming the Tidmouth, Knapford and Elsbridge Light Railway. In 1916 the NWR completed a double track tunnel and Tidmouth's usefulness as a harbour started to be explored.
- In the television series, the tunnel was replaced with Henry's Tunnel as the one where Henry found the elephant.