Accordingly, the London and Brighton Railway had their line directed through a purpose-built tunnel instead of a cutting.

The original plans for the railway did not involve a tunnel at this location, but engineers had not predicted that the owner of Patcham Place, a Major Paine, would refuse permission for a cutting to be constructed through land that he owned.

Partway through construction, the tunnel suffered a collapse, although no fatalities were attributed to the incident.

[1] Between October 2018 and February 2019, Patcham Tunnel was subject to a series of scheduled repairs as part of a £300m improvement programme on the Brighton Main Line; work was undertaken to reduce the ingress of water and re-lay the tracks during temporary closures.

[5][6] However, occasional closures of the line due to flooding of Patcham tunnel have persisted even after these remedial works were completed.