By December 1914, Hetherington had moved to
Wormwood Scrubs Naval Air Station in London, as Divisional Transport Officer for the armoured car formation which was being assembled there. One of his engineer officers,
Robert Francis Macfie, had been investigating the use of
Holt tractors which ran on
continuous tracks. When Macfie suggested that they be used to cross trenches on the battlefield, Hetherington joked that it would be better to "take a thing like the
gasometer at the Oval, put on a couple of wheels like the
Earl's Court Wheel, put your mechanism inside and put in some decent guns like
12-inch naval guns, then you can cross the
Rhine". Although initially suggested in jest, Hetherington began work on a detailed design aided by his subordinates, which he submitted to his commanding officer,
Murray Sueter, and became known as the "Hetherington Proposal". The three huge wheels were intended to be driven by electric motors using the power generated by submarine-type diesel engines. Including the 12-inch gun armament which weighed 47 tons, the total weight was calculated at 800 tons. Sueter persuaded Hetherington that this would be impossibly large, so a second design was produced, the "Revised Hetherington Proposal", this time of 300 tons, with three 40 foot diameter wheels and an armament of three twin turrets for 4-inch guns. At the end of January 1915, Sueter forwarded this design to
Winston Churchill, the
First Lord of the Admiralty who was desperate to find a way to overcome the static
trench warfare which had developed, despite the fact that this was not really naval business. Churchill forwarded the plan to
Jackie Fisher, the
first Sea Lord, who passed it on to his gunnery expert,
Percy Scott, whose opinion was that it would be too easily targeted by enemy artillery before it could be used. However, that was not the end of the line for the Revised Hetherington Proposal, because in early February, Hetherington attended a dinner at
Murray's Cabaret Club in
Soho hosted by the
Duke of Westminster, who had aggressively commanded an armoured car section in Samson's Dunkirk wing. Also present were
Albert Gerald Stern, a former banker and one of Hetherington's officers, and
James Radley, the racing driver. The duke was enthused by Hetherington's account of his machine and invited Churchill to a dinner party on 17 February where Hetherington was able to explain his proposal in detail. As a direct result, Churchill established the Landship Committee, which was chaired by
Eustace d'Eyncourt, the
Director of Naval Construction, Stern was the secretary and Hetherington was joined by Colonel Wilfred Dumble of the
Royal Naval Division who had previously managed the
London General Omnibus Company. Although Hetherington's proposal was quickly found to be impracticable,
William Tritton did construct a much smaller machine on the "Big Wheel" principle for the committee, but after numerous problems, it was abandoned on 8 June. The committee also followed several other lines of inquiry. This included a trip to Paris by Hetherington in April to investigate a new type of
gel-filled laminate armour which proved to be useless. On 30 June 1915, Hetherington himself drove a
Killen-Strait tracked vehicle across broken ground and barbed wire in a demonstration at
Wormwood Scrubs, attended by Churchill and
David Lloyd George, the new
Minister of Munitions. Although the Killen-Strait tractor was too small to be useful, the trial would lead to the adoption of tracked propulsion for
Little Willie, the first prototype tank. In January 1916, Hetherington was given command of a detachment from No. 20 Squadron, Royal Naval Armoured Car Division, that provided the crew for "Mother", the
prototype of the
Mark I tank, when it was demonstrated to senior naval and military officers and government officials at
Hatfield Park in
Hertfordshire. In January 1918, Major Hetherington was created a Commander of the
Order of the British Empire for "services in connection with the origination of the Tanks". In November 1919, the
Royal Commission on Awards to Inventors concluded that "great credit" was due to Major Hetherington for his part in the development of the tank, but no monetary reward was due because his work had been within the scope of his duty.
Revised Hetherington Proposal Specifications • Armament: 3 twin 4-inch gun turrets with 300 rounds per gun • Horse power: 800 h.p.
Sunbeam Diesel engine with fuel for 24 hours • Total weight: 300 tons • Armour: 3 inches • Diameter of wheels: 40 feet • Tread of main wheels: 13 feet 4 inches • Tread of steering wheel: 5 feet • Overall length: 100 feet • Overall width: 80 feet • Overall height: 46 feet • Clearance: 17 feet • Top speed on good going: 8 miles per hour • Top speed on bad going: 4 miles per hour ==Later career==