The tour also explores how the Bank redevelopment project utilised the original 1890 station to build the current platforms and passageways.

[2] King William Street opened on 18 December 1890 and was constructed from a large masonry station tunnel, accessed from the surface by a lift shaft or spiral staircase.

In 1895, a central island platform with tracks each side was constructed to enable two trains to occupy the station at once; however, capacity was still restricted.

Access today is via a manhole in the basement of Regis House, a contemporary office building, where the original cast iron spiral staircase leads down to platform level.

The original running tunnels north of Borough station remain, although when the Jubilee line extension was built in the late 1990s, the old southbound tunnel was cut through as part of the construction works at London Bridge station in order to provide the lift shaft situated at the south end of the Northern line platforms.