When the First World War got bogged down in trench warfare, thousands of miles of narrow-gauge railways were laid to supply the front lines on both sides. Although many steam engines were used, they were vulnerable to enemy fire, and lightweight petrol-engined locos were developed. One of the leading manufacturers was Motor Rail, of Bedford, who had developed a gearbox with the same number of speeds in both directions--those derived from road vehicles had only one in reverse! Over 260 of these distinctive armour-plated machines were built in 1917-18, helping the Allied advance in the latter stages of the war. Many were sold for civilian use after the war, one of the users being the Leighton Buzzard Light Railway, Bedfordshire, for whom they hauled sand trains until the 1950s. The railway is now one of the leading narrow-gauge heritage lines in England, and has two of these in its collection. War Department No 3098, pictured, is in working order, and on long-term loan from the National Railway Museum collection. No 2182, one of the rarer fully-armoured type, was donated by the National Army Museum, and will be restored to working order when the necessary funds have been raised.