Singer Gazelle Estate Car was added to the Saloon and Convertible which were modified and became Series II in the autumn of 1957. The capacity of the petrol tank is increased to 10 gallons and overdrive became optionally available.
In the spring of 1958 a 1494-cc overhead-valve engine and recirculating ball type steering gear were introduced; the range then became known as the Series IIA.
Series III was introduced in September. Changes include a different front end in which grilles with horizontal bar replaced the pressings on each side of the radiator grille, cowled headlamps and a bonnet motif.