When "The Motor Cycle" road tested an example of the newly introduced Ariel 4G Mark II Square Four during 1953 they summed up the machine in the following manner "A unique high-performance mount with gentle manners and outstanding acceleration". The Mark II had been introduced for the 1953 season incorporating a revised cylinder head to which two alloy inlet manifolds were bolted with separate exhaust pipes for each cylinder. Square Fours had, since their introduction, suffered from over heating rear cylinders under extreme circumstances which the revised cylinder head largely cured. A further benefit of the new head was an increase in power output to 40 bhp at 5,600rpm. The cycle parts were carried over from the Mark 1 but the colour changed to a light Wedgewood blue for a couple of seasons before reverting to the traditional red livery. A new one gallon oil tank, full width alloy hubs and a headlamp nacelle were introduced for the 1956 season establishing the Square Fours final form.

This example was restored during 2009, both cosmetically and mechanically and is a fine example of the Square Four in its final form. The vendor informs us that it runs very well and he believes it to be correct in all major respects.