A little way north of the Uber boat station by the Tower Of London you might notice a small cylindrical building called the Hydraulic Tower,

Today it carries a water main, hence the name, but its heritage is rather different.

Quite possibly you have used the nearby Tower Hill underground station which is not far from the site of the old Tower Of London station which opened in 1882 as a terminus for the Metropolitan Railway.

Even this, though, was not the first railway on Tower Hill.

In 1870 the Tower Subway, a 2’6” narrow gauge railway, was built from Tower Hill under the Thames to Vine Lane off Tooley Street by London Bridge station. There was a single carriage which was pulled by cables connected to a static steam engine at each end. It proved unreliable and a passenger died in an accident with the lift.

In 1871 the railway was taken up and it became a pedestrian tunnel with a toll of a halfpenny. It attracted a million transits each year. A bit of maths: 480 halfpennies to the pound, divide by 52, works out at £40 per week which was not a bad bit of bunce in the late 1800s – equivalent to £4,700 in 2020.

In 1898 it went out of business because of the free crossing afforded by Tower Bridge which opened in 1894. Today it carries a water main and phone lines. You can, however, see the original entrance.

The tunnel was bored by pioneer engineer James Greathead using an adaptation of Marc Brunel’s tunnelling shield as used to build the Wapping Tunnel.

The Tower Subway features on my Tower Hill tour.