Built in 1863, the tunnel was built for trains running from King's Cross York Road (an annex of the main station), towards Moorgate. Although the station was demolished in the 1970s, the tunnel survives.

With an overall length of 350m, the opening section of the single-bore tunnel runs in a straight line for 200m. It then hits a fork, with one tunnel reaching a dead-end, the other sharply curving to the East, opening out to an air shaft.