Work on Withcall Tunnel got underway in January 1852 with the driving of a 10-foot heading through sandstone and chalk. The Louth & Lincoln Railway’s original plan was for a bore of 803 yards but this was extended to 971 yards when a revised route was authorised. Construction was beset by problems with bad weather causing frequent delays. In October 1874, a deluge of water washed navvies out of the tunnel. A month later, bricklayers went on strike because their hands were being scalded by wet lime. And December saw the death of a workman who was struck by a wagon.
The first goods train passed through the tunnel on 26th June 1876, with passenger traffic starting in the following December.
The tunnel is straight but no light can be seen at the other end because the summit of this part of the line is located around 300 yards in from the eastern portal. The climb up to and within the tunnel (1 in 54) often caused difficulties in wet conditions - some locomotives required two or more attempts to reach the top. Smoke could become so dense that the footplate crew would kneel on the floor, covering their faces with wet handkerchiefs.
An oversight by the architect resulted in no refuges being constructed - an unusual and potentially dangerous feature for a tunnel of this length.
Today, the portals are bricked up but doorways are provided for access. Humidity levels are high and temperatures stable - ideal conditions for bats. The structure is now a hibernaculum and has SSSI status. Although wet at its western end, Withcall Tunnel remains in excellent condition despite a 50-year absence of regular maintenance. The last train passed through on 17th September 1956.