In November 1944 what was left of the Triumph Motor Company and the Triumph brand name were bought by the Standard Motor Company and a subsidiary "Triumph Motor Company (1945) Limited" was formed with production transferred to Standard's factory at Canley, on the outskirts of Coventry. Triumph's new owners had been supplying engines to Jaguar and its predecessor company since 1938. Following a "considerable argument" between Standard-Triumph Managing Director, Sir John Black, and William Lyons, the creator and owner of Jaguar, Black's objective in acquiring the rights to the name and the remnants of the bankrupt Triumph business was to build a car to compete with the soon to be launched post war Jaguars.

The pre-war Triumph models were not revived and in 1946 a new range of Triumphs starting with the Triumph Roadster was announced. Because of steel shortages these were bodied in aluminium which was plentiful because of its use in aircraft production. The same engine was used in the 1800 Town and Country saloon, later named the Triumph Renown, which was notable for the razor-edge styling chosen by Standard-Triumph's managing director Sir John Black. A similar style was also used on the subsequent Triumph Mayflower light saloon. All three of these models prominently sported the "globe" badge that had been used on pre-war models. When Sir John was forced to retire from the company this range of cars was discontinued without being directly replaced, sheet aluminium having by now become a prohibitively expensive alternative to sheet steel for most auto-industry purposes.

In the early 1950s it was decided to use the Triumph name on sporting cars and the Standard name on saloons and in 1953 the Triumph TR2 was launched, the first of a series that would run through to 1981. Curiously the TR2 wore a Standard badge on its nose and the Triumph globe on its hubcaps.

Standard had been making a range of small saloons called the Standard Eight and Ten and had been working on a replacement for these. The success of the TR range meant that Triumph was seen as a more marketable name than Standard and the new car was launched in 1959 as the Triumph Herald; the last Standard car to be made in the UK was replaced in 1963 by the Triumph 2000 .

 

In December 1960 the company was bought by Leyland Motors Ltd with Donald Stokes becoming chairman of the Standard Triumph division in 1963. Further mergers led to the formation of British Leyland Motor Corporation in 1968.

In the 1960s and 1970s, Triumph sold a succession of Michelotti-styled saloons and sports cars, including the advanced Dolomite Sprint, which, in 1973, already had a 16-valve four cylinder engine. It is alleged that many Triumphs of this era were unreliable, especially the 2.5 PI (petrol injection) with its fuel injection problems. In Australia, the summer heat caused petrol in the electric fuel pump to vapourise, resulting in frequent breakdowns of the 2.5 PI and TR6 models. While the injection system had proved itself in international competition, it did lack altitude compensation for the adjustment of mixture at altitudes greater than 3000 ft (1000 m) above sea level. The key reason for the Lucas system's unpopularity, was that Lucas was not inclined to further develop it on the one hand allied to the unwillingness of Standard-Triumph dealers to attend factory and field-based training courses dedicated to this propulsion method.

For most of its time under Leyland or BL ownership the Triumph marque belonged in the Specialist Division of the company which went under the names of Rover Triumph and later Jaguar Rover Triumph apart from a brief period in the mid 1970s when all BL's car marques or brands were grouped together under the name of Leyland Cars.

The only all-new Triumph model launched under Rover Triumph was the TR7, which had the misfortune to be in production successively at three factories that were closed - Speke, the Leyland-era Standard-Triumph works in Liverpool, the original Standard works at Canley, Coventry and finally the Rover works in Solihull. The four-cylinder TR7, its eight-cylindered derivative the TR8, and its still-born fastback variant the Lynx, were dropped when the Solihull plant ceased making road-going cars (the plant continues to build Land Rovers.)

The last Triumph model was the Acclaim which was launched in 1981. The trademark is currently owned by BMW.

Only one example of this car was ever made by Triumph. The Triumph TR1 prototype was unveiled in October 1952 at the London Motor Show. The TR1 name was never officially used.The car was built using existing components with an engine from a Standard Vanguard, suspension from the Triumph Mayflower and a chassis from the pre war Standard Flying Nine. Problems arose when the car came to be driven as it was a poor handler, had a top speed of barely 80 mph (129 km/h) and was an overall disappointment to its early viewers, one of whom, Ken Richardson of BRM, described it as a 'death-trap. The car, which never went into production, was withdrawn, and the designs taken back to the drawing board, and a year later the new improved Triumph TR2 was unveiled. It is unknown whether the original prototype exists today.