In the early 20th century, the Metropolitan Railway (MR) penetrated Hertfordshire and Buckinghamshire with its suburban railway, enticing Londoners with its "Metro-Land" advertising campaign promoting the new railway as an opportunity to live in a rural location with easy transport to central London. The MR was also intent on providing a connection from Watford and planned a branch line from via . The MR purchased a swathe of land from Gonville and Caius College, Cambridge along the planned route, and Parliamentary approval for the branch was granted in 1912. The project was hampered by disagreements with the Watford Borough Council and by the outbreak of World War I in 1914, and construction of the branch did not begin until 1922. The MR experienced difficulties running the line across the River Gade and the Grand Junction Canal, and this pushed costs up to £300,000.