Martyn was then aged 16 when he built this model of the Alvis saladin. Although the prototype was 6×6, in Martyn's model the middle axle was not driven; the first and third were driven and the first and second steered.

The turret was mounted on a 168 Ball Race, but with a 3½" Gear for the upper race, driven by a pinion from below. Also the gun could be raised and lowered, driven from a shaft up the middle of the bearing.

All movements were operated from levers in the driving position, below the hinged Flat Girders in front of the turret.