The following month a special committee of the Admiralty Air Department, among whom was Flight Commander T. G. Hetherington, designed the superstructure which consisted of armoured bodywork and a single fully rotating turret mounting a regular water-cooled .303 in (7.7 mm) Mk I Vickers machine gun.

The first three vehicles were delivered on 3 December 1914, although by then the mobile period on the Western Front, where the primitive predecessors of the Rolls-Royce cars had served, had already come to an end.

[6] Six RNAS Rolls-Royce squadrons were formed of 12 vehicles each: one went to France; one to Africa to fight in the German colonies and in April 1915 two went to Gallipoli.

From August 1915 onwards these were all disbanded and the materiel handed over to the Army which used them in the Light Armoured Motor Batteries of the Machine Gun Corps.

The armoured cars were poorly suited to the muddy trench filled battlefields of the Western Front, but were able to operate in the Near East, so the squadron from France went to Egypt.

[1][7] They were a major advantage to the Free State in street fighting and in protecting convoys against guerrilla attacks[citation needed] and played a vital role in the retaking of Cork and Waterford.