In his 1845 description of the tunnels, James Stonehouse spoke of a tunnel running between Smithdown Lane and the Great Tunnel. He said that it was about 40 yards long and 15 feet wide. Also that it started 9 feet high but widened out to become 25 feet high, in the shape of a seaman's speaking trumpet. He included it, as seen above, in his sketch of the tunnels' layout. He added that at the end was a vault heading north for about 50 feet, to the edge of Williamson's land. This would have run (under ground) from the mouth of the Great Tunnel to Williamson's boundary wall, which is still intact at this point today.

It becomes apparent that the 'seaman's trumpet' tunnel was a major entry and exit point to the works. Leading into the lower part of the Great Tunnel, it would no doubt have been used to bring the spoil out when the latter was being dug.

In the 1960s, when a block of flats was being built over this point, work was temporarily stopped when a hole appeared in the ground. It led into the seaman's trumpet tunnel and the hole was capped and the location of the building changed slightly to avoid it.

Today, the location is visible through a gate on Smithdown Lane (with part of Williamson's original boundary wall still in place on the right) ...