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".

[2][page needed] The Admiralty replied on 16 April 1916, saying that in view of the wartime emergency, it would be inappropriate to insist on peacetime safety measures.

"[4] The Board of Trade replied that they had no jurisdiction in the matter, and the Admiralty would have full responsibility for the operation of what amounted to a military railway.

[2][page needed] Construction started, and the Great Northern Railway took responsibility for the engineering of the new line: it was to be a little over five miles in length.

The Admiralty paid the Great Northern Railway £500 annually for the use of Sleaford station, used by the branch passenger trains.

[2][page needed] There were three passenger stations on the branch: Slea River, not far from the junction with the GNR line, Cranwell, and East Camp.

[8] After coming under repeated pressure to reduce the deficit,[9] the line ceased to carry regular passenger traffic in November 1926, [10] with a consequent reduction in running costs.

[12] Five locomotives owned by the contractors Logan and Hemingway are known to have worked at Cranwell; these were all Manning Wardle 0-6-0 Saddle Tanks, with numbers: 3, 4 Epworth, 5, 7 Bletcher and 8.

[13] A surviving Logan and Hemingway locomotive of the type used on the RAF Cranwell Railway (a 0-6-0 Manning Wardle saddle tank originally known as Number 10, but which now goes by the name of Sir Berkeley[14]) is owned by the Vintage Carriages Trust.

[16] The station at Slea River has been demolished and East Camp is occupied by residential estates for the soldiers based at RAF Cranwell.