This viaduct over the Darent Valley was built by the independent "Sevenoaks Railway", incorporated in 1859 to link the "Chatham" main line with the market town of Sevenoaks. The branch was initially single-track, seeing its first services on 2nd June 1862, but the viaduct was built to accommodate two tracks from the outset, because the line was doubled in the following year. (Detail from "Kent Rail").
Ian