The first generation of the Alvis TD 21, known as the Series I, was introduced in 1958. These cars were available in saloon or drophead coupe body styles, which were built by the coachbuilder Park Ward. Power for the Series I came from a 3.0L inline six engine sending drive to the rear wheels via a 4 speed manual, or 3 speed automatic transmission. The Series I was built until 1961, when it was replaced by the Alvis TD 21 Series II.