Chiltern Main Line

The Chiltern Main Line is an inter-urban, regional and commuter railway, part of the British railway system. It links London and Birmingham, England's two largest cities, by a 112-mile route via High Wycombe, Banbury, and Leamington Spa. It complements the West Coast Main Line, the main InterCity route between London and Birmingham. The name Chiltern Line was invented as a marketing name for the line by Network SouthEast in 1985. In reference to the Chiltern Hills.

More information on the Wikipedia page.