Captain Eustace Tennyson D'Eyncourt (1868-1951), naval architect, first cousin once removed of Alfred, Lord Tennyson, and newly-appointed chair of the Land Ship Committee.

February 20 1915, London–Early in January, Churchill had urged the production of “armoured steam tractors” in a letter to PM Asquith. The idea was given a new impetus in Churchill’s ever-busy brain early in February at a dinner held by the Duke of Westminster. There, Churchill met Maj. Thomas Hetherington of the Royal Flying Corps, who was busy developing armored cars. Hetherington had proposed to his superiors in the Air Department the building of

…a giant wheeled vehicle for cross-country traveling, which was to have wheels of such large diameter and to be provided with such great propelling power that it could travel indiscriminately over all but the greatest natural and artificial obstacles. It was to be armoured against hostile gun-fire and to be armed with a naval 12-inch gun.

Hetherington spoke to Churchill about his ideas, and Churchill was immediately enamored, telling him to submit a proposal to the Admiralty; Hetherington did so the next day. Churchill promptly ordered one of his naval architects, Captain Eustace D'Eyncourt, to examine Hetherington’s proposal and draw up a design.

Simultaneously, the Air Department’s plans were proceeding at the urging of Hetherington, and with Churchill’s backing. On February 16, a prototype “land ship,” a tracked armored car (as yet without an engine) was pulled around the Horse Guards Parade at Whitehall by a white horse. This incredible sight encouraged Churchill, though it drew derision from the War Office.

On February 20, although sick with the flu, Churchill called together an official Admiralty conference on these “land ships.” An official “Land Ship Committee” was formed, to be chaired by D'Eyncourt. Churchill decided that secrecy was paramount, and wanted to obfuscate the name of these vehicles as much as possible. An early suggestion was “water-carriers for Russia”; after it was pointed out this would quickly be shortened to the less polite “WCs for Russia”, it was decided to use “water tanks for Russia” instead.

Sources: Randal Gray, Chronicle of the First World War (Volume I); Carlo D'Este, Warlord.