1951; Standard eight introduced incorporating newly developed 803CC "SC (small car) engine.
1957; Triumph Herald (code name Zobo) begins to develop under the guidance of Alick Dick, Harry Webster (chief designer) and Martin Tustin (General Manager). Original design concept incorporated a monocoque body shell. Eventually the realities of financial constraint led them to use a chassis and separate body shell. This chassis was to be the "jig" foundation for a whole range of vechiles. Body designed by Giovanni Mechelotti. Went on sale April 1959.
1960-62; The development of "Bomb" a new sports car utilising the SC engine unit (1147cc) and Herald chassis. "Bomb" became known as the Spitfire 4, with 
the body again designed by Michelotti. The car utilised much of the Herald running gear including engine, gearbox, suspension - the prototype even incorporated the same instrument gear and, the car almost went into production without a rev counter. High compression engine (9.0:1), twin SU carburettors and a high lift cam provided 63bhp. Rear suspension consisted of a transverse mounted fixed leaf spring, radius arms & telescopic shock absorbers. Disc brakes fitted at the front. The steering gave the car a smaller turning circle than a London Taxi. Overdrive was optional. The Spitfire 4 was launched at the Earls Court Motor Show in 1962.
Spitfire chassis; Cut & shut Herald chassis but without the out riggers to support centre of car. The sills supplied strenght and were and still are vital to the structure and safety of the vehicle.
Early production of the body shell at the Forward Radiator Works, Bordesley Green, Birmingham used low quality toolong, which was uprated once the Spitfire 4 became a success. Hardtop introduced as an option in late 1963.
1963; Spitfire GT project begins to develop using fastback hardtop and 1598cc Vitesse engine. The Vitesse engine was developed from the 1959 Vanguard 6 unit; this was essentially a "small car" four cylinder unit with two extra cylinders tacked on.
December 1964; Spitfire 4 MKII introduced. Engine power increased during production of MKII to 67 bhp. Trim revised.
October 1966; GT6 (formerly the Spitfire GT), revealed with fixed fastback body shell and a 1998cc engine.
January 1967; Spitfire MKIII introduced with long stroke 1296cc engine of 75bhp. The "4" tag became redundant. First of the Spitfire range to incoporate negative earth electrical systems. Trim revised, external changes consisted of raised bumpers to conform with new regulations. Reverse lights installed. Fold down hood replaced detachable type.
July 1968; GT6 MKII begins porduction introducing revised and much improved rear suspension. October 1970 GT6 III released which incorporated radically restyled front and rear end by Michelotti to fit in with the current Triumph range.
Spitfire MKIV; November 1970 to December 1972 (USA) and to December 1974 (all markets). The Michelotti restyled front and rear ends matched the lines of the new GT6 MKIII. New angular hardtop designed at Coventry. Rear suspension uprated by relacing the solidly fixed rear spring with a pivoted unit. The "swing spring" stopped much of the interesting cornering problems of the earlier models. All synchromesh gearbox fitted, and final drive ratio changed from 4.11:1 to 3.89:1 (3.37:1 in overdrive). Power output restricted by USA environmental regulations to 63bhp. Interior modified and became similar in apperance to the GT6 MKIII. Dashboard modified so instruments were in front of driver rather than in centre of dash panel, as found on all previous models.
July 1973; USA models received 1500cc engine, due to lost sales caused by bhp reduction. In the same year all models had rear suspension track increased by 2". "D" type overdrive replaced in August by "J" type.
December 1973; GT6 MKIII ceases production.
Spitfire 1500; introduced January 1973 (USA) and December 1974 (everywhere else). Bigger 71bhp, 1493cc engine, New single rail gearbox from Marina with the same specified ratios as the MKIV. Minor styling changes.
1977; New seats, trim and TR7 style switch gear.
August 1980; The last Spitfire rolled off the production line.
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