The Cranwell branch was a military branch line railway in Lincolnshire, England. It connected the Royal Naval Air Station (RNAS) at Cranwell to the main line at Sleaford. It opened in 1917 from Sleaford railway station and it joined the Great Northern Railway. RNAS Cranwell was intended for training pilots and aircrew during the First World War. Control soon passed to the Royal Air Force in 1918, and the location became known as RAF Cranwell. A public passenger service was operated from the outset, and there were three stations on the branch. The passenger service was loss-making and it closed in November 1926, but the goods service on the line continued until closure in 1956. A new military base In the early part of the First World War the British Admiralty were seeking a location for an airfield to train naval pilots. In 1915 the Aerodrome Selection Committee identified a "large stretch of flat country on top of the heath above Caythorpe". The location was near Cranwell, and was quickly selected. The Admiralty took possession of Cranwell Lodge Farm, which was the majority of the land required, on 23 November 1915. The location was to become the Royal Naval Air Service Training Establishment, Cranwell. The naval personnel were held on the books of HMS Daedalus, a hulk moored on the River Medway. Many sources assert that the RNAS was itself named HMS Daedalus. Construction of the accommodation for servicemen and aircraft soon started: a considerable quantity of materials needed to be brought to the location, and at the time public roads were barely adequate. The winter of 1915-1916 was hard, and transport by road to the site for construction proved very difficult. A temporary railway track was laid by the contractor; it was laid directly on the ground without any attempt at earthworks. The gradients were so severe that two locomotives were needed to pull five loaded wagons, and the line was nicknamed "the switchback". A proper railway It was decided to provide a proper railway on a permanent basis using the alignment adopted by the contractor but improving it for full railway usage, for both goods and passenger operation. The Admiralty wrote to the Board of Trade on 6 March 1916 stating that a passenger railway was to be provided to the new establishment, and an inspecting officer, Col Druitt, visited on 20 March 1916. Druitt advised that if