It was the first appearance of the new four cylinder 1,489 cc (90.9 cu in) B-Series I4 engine with a pair of 1+1⁄4 in (32 mm)-bore twin-choke SU carburettors, delivering 60 bhp (45 kW),[3] driving the rear wheels through BMC's new four-speed manual gearbox with synchromesh on the top three ratios.

Hydraulically operated Lockheed 10 in (254 mm) drum brakes were fitted to front and rear wheels.

[citation needed] The similar Wolseley 4/44, first sold one year earlier, used the 1250 cc engine from the MG TF.

Although visually similar, the MG has lower suspension and only the front doors, boot lid, and roof panels are shared.

[7] A Varitone model featured larger rear window and optional two tone paintwork, using a standard Pressed Steel body shell, the rear window opening enlarged in the Morris Motors body shop, Cowley, before painting.

[2] The Mark III announced 2 February 1959[9] was nearly identical to the Riley version (the 4/68) of the new Pinin Farina-designed midsize BMC saloon line.

All versions (including the Austin A55 Cambridge Mark II, Morris Oxford V and Wolseley 15/60) were produced by the British Motor Corporation (BMC).

The car featured BMC's 1489 cc B type engine but, in the MG Magnette III (and its Riley sibling), performance was enhanced by fitting twin S.U.

[10] The interior featured a walnut veneer facia panel, door cappings and leather upholstery as well as safety glass windows.