Box Tunnel East Portal (MLN19912)

The Box Tunnel East Portal is a late 1930s structure built of Bath stone ashlar, with repairs and alterations primarily in engineering brick. The facade features a plain projecting band as a parapet and projecting piers on either side, which are banded and vermiculated. The lower parts of these piers have been reconstructed in engineering brick. The main tunnel mouth is very tall, with a semi-circular arch of 30ft (9m) span. The upper half of the arch is formed of voussoirs with a keystone featuring vermiculated rustication; originally, these voussoirs continued to ground level, but the remaining lower voussoirs have been recreated in engineering brick, and the area below finished with plain engineering brick. A second, lower, semi-circular arch of engineering brick was also constructed around 1938, flush with the original, and a further segmental arch of engineering brick appears approximately 10m inside the tunnel, with an opening above it.

On the north (Up) side, a later raked retaining wall of red/purple brick adjoins the north pier and descends as stairs eastward, parallel to the tracks. Modern steel railings line these steps, which lead between the tracks and the former entrance to a quarry/ammunition depot tunnel siding located around 10m east of the main portal. This latter tunnel entrance has a reinforced concrete, angled, rectangular portal. A raked, rubble retaining wall with angle quoins rises behind this siding portal. It connects to another tall retaining wall constructed in the 19th century, and running eastward to form the north (Up) side of the cutting, likely built to accommodate the quarry siding. On the south (Down) side, the original 1841 portal adjoins a raked, rubble-lined cutting wall which rises in a step to approximately two-thirds of its height.