The line was closed completely a hundred years later in 1958, but the tunnel was still being used by members of the public, so the portals were bricked up in 1961.

During 1970s and 1980s, there were collapses inside the tunnel and in 2009 the restoration of the passenger line could not continue due to the damage.

Construction began in 1847 with the sinking of seven vertical shafts, but the tunnel, which was 1,747 yards (1,597 m) in length, was not completed until 1853, work having been interrupted and slowed at times due to lack of funds.

[1] The lack of funds led to alternate lengths being proposed, including a 1,606 yards (1,469 m) route which would have meant a steep incline.

[2] During construction illegal drinking houses were built and riots occurred in navvies' temporary accommodation near the tunnel's northern mouth.