Experience to date indicates that the first phase will probably be the dropping of large numbers of parachute troops outside the aerodrome boundaries under cover of an intensive low-flying attack on the station buildings and perimeter defence posts.

In this way the enemy will hope to surround the aerodrome and the second phase, probably following almost immediately, would be a concerted attack by the parachutists with the object of finally overpowering the defence posts thus clearing the way for the immediate landing of large numbers of troop-carrying aircraft upon the aerodrome itself.The RAF started looking for a suitable vehicle at the end of May 1940 and by 4 June they settled on the design destined to be known as the Armadillo.

This vehicle was a flat-bed truck, on the back of which was mounted a box-like fighting compartment in which soldiers could stand and fire small arms or use one or two crew-served weapons.

Using a wide range of trucks conscripted from civilian service, the first 20 were delivered on 7 June and the complete consignment of 312 vehicles within just a couple of weeks.

On 20 June, the Air Ministry ordered another 300 vehicles; these Mk II Armadillos would mostly be based on a standard Bedford OL 1½ and 3 ton chassis.

A later Mk III Armadillo was always based on a three-ton chassis, it had a slightly smaller fighting compartment now occupying only the front half of the truck's flat bed.

[2][3][4] In April 1942, a small number of Mk IIIs had their shingle protection replaced with "plastic armour" - a mixture of bitumen (or pitch) and granite or similar stone chippings.

To counter such a view, instructions emphasised its use as a mobile unit, not a static fort and it was to be reserved for the defence of the airfield and not given other tasks such as transporting ammunition or being driven off to find parachutists.