Introduced September 1934 and known by its model year (1935), it continued unchanged as the Series I following the marketing decision to move away from the cosmetic yearly changes to a policy of major upgrades. The changeover occurred at the beginning of June 1935 but the only difference was the change in the chassis numbers from the 35/E prefix to S1/E. There had been minor changes since its introduction and these continued until the major changes in the Series II version.

The early Series I models had fabric-disc universal joints and a badge design incorporating the letters"EIGHT". Later models had the Arabic figure "8". Solid steering wheel gave way to a flexible rubber covered item during the Series I production.

Announced in August 1937 the Series II had major cosmetic changes came with the introduction of "Easiclean" type disc wheels replacing the spoked Magna wheels. The characteristic chromium plated radiator shell was replaced with a painted shell finished to match the body colour. The Series finished August 1938 with the announcement of the Series E.

Throughout production the Morris Eight was available as a saloon with two or four doors, in fixed or sliding head versions. Open models were the Two-seater and Four-Seater Tourer. Open models and all fixed head saloon models were upholstered in "Karhyde" leathercloth. Sliding-head version of the saloon in real leather.

The van version "Morris Eight 5 cwt" continued to be produced up to December 1939 although designated Series I.