The maximum armor thickness was 9 mm/0.35".
It remained in service until 1942.
Usage in World War I
In October 1914 the Royal Naval Armoured Car Division was formed by Commander E. L. Boothby RN in which the first squadron was outfitted with Rolls Royce armored cars. Once the trench warfare stage started the squadrons were used in anti-invasion patrols along the east coast of England.
The first RNAS squadrons, under the command of the Duke of Westminster, were first used in France in March 1915. The first usage was to patrol the coastal areas along the Belgian and French coasts.
The cars were turned over to the British army, but they showed little interest in them.
They were used in the North West Frontier of India, Gallipoli, German South West Africa, and in Uganda.
At Gallipoli the RNAC Squadrons Nos. 3 and Nos. 4 were sent but they spent most of the time situated in trenches to prevent their destruction by artillery fire.
In German South West Africa the Rolls Royce squadrons found it difficult to go on the soft ground along the coast and had to be moved by rail inland. They were used for ambushes and the headlights were used to light up German targets.
Nine Rolls Royce armored cars and 28 cars and ambulances were formed into a rescue group under the command of the Duke of Westminster. Their mission was to rescue the survivors of the sunk SS Tara located in North Africa. They crossed log distances of desert and succeeded in rescuing all the survivors.
After World War I
The Rolls Royce armored cars remained in service with the British Army until 1922.
Usage in World War II
Some were used in India.
Armored Car, Rolls-Royce (1920 Pattern) in the Western Desert
Used for patrolling against Italians in Western Desert during early part of war.