from the vertical. The depth varies from 25 ft. to 30 ft. maximum and the width at the base also varies, being wider on the rear (long north east to south west) face and at its narrowest on the southern and northern flanks. It is 15 ft. wide. There are no caponiers or counterscarp galleries in the ditch, the only known major British Defence work to adopt a purely passive defence posture. There is much evidence of the 1907 siege works in this ditch, three of the counter-mine shafts still survive, now mostly covered up with debris and rubbish (post 1962). Near the RSJ which spans the moat are seen five massive cracks and more repair work, again from the siege trials of 1907, but this time, the hole in the base of the ditch was not dug by the defenders but was the result of a failed "camoflet" or "petard". Accounts vary as to the title of the device used, but it was a type of tunnel driven from the attacker's side along the length of the moat to here and exploded. The first left the now mostly back-filled crater but at the second attempt blew a section of the wall outwards causing the damage still to be seen. After the sale of Fort Luton to Kent County Council the ditch fell into rapid disuse and became an illegal dump for all manner of refuse. A great pile of debris has been allowed to build up beneath and to either side of the drawbridge and beneath the RSJ. The disuse of the ditch has also caused much growth of vegetation. The fort in use From 1914 to 1919 the fort was used as a Transit Barracks for troops en route to Europe. From 1920 till 1933 it was used as a store. In 1938 conversion of the fort to a Gun Operations Room (GOR) began. In August 1939 it opened as GOR for the 27th. AA Brigade (Thames and Medway South) Gun Defended Area. Brigadier C.W. Bayne-Jardin D.S.C. M.C. was in command until relieved circa 1942, after which other officers of the same rank continued in command until December 1945. From 1945/6 to 1961 the fort was used by Army Cadet Force and T.A. Summer camps. In 1961 or 1962 it was sold to Kent County Council (D100 procedure) for educational uses, but the KCC just wanted the land