The MG 14/40 or MG 14/40 Mark IV was launched in 1927 and was produced until 1929 with approximately 700 cars manufactured. It had its origins in the MG 14/28 and was similar to the Morris Oxford flatnose. The flatnose term was used to describe the new radiator/grille fronts of the cars. Morris had redesigned his cars to incorporate the flat radiator design of American cars. If you recall, the MG 14/28 and earlier cars all had the rounded bullnose radiators which gave them a tractor-like appearance at the grille. In 1926 the bullnose was dropped and the flat radiators were used, and the radiator cooling surface was increased. The 14/40 was manufactured at the Edmund Road works in Cowley, Oxford where MG manufacturing had moved in September of 1927. It was the first model to feature the MG Octagon badge on the radiator. Apart from the flatnose, the 14/40 did not look very different from the 14/28. The chassis of the 14/40 was heavier and wider to allow more room in the body. The chassis was also stiffer which made the car easier to handle. The engine was updated to 35 bph (brake horsepower) and the brakes were changed to eliminate the servo. The name 14/40 promoted the additional horsepower, which while improved, was 37 bph and not 40 bph. The designation of Mark IV is not clear, and some think that it was named for the fourth year of production of the 14/40.
The car bodies offered included a Featherweight Fabric Saloon and a fixed head (hardtop) and drophead (convertible top) coupé. The MG works continued to distinguish themselves from the Morris Motors brand, and led to the creation of the M.G. Car Company in 1928. The new M.G. Car Company and Morris Motors were owned personally by William Morris.
A new 18 hp overhead camshaft six-cylinder engine had been developed by Hochkiss and Kimber realized that this engine could be used to build a bigger sports car to compete with the Bentley. To design the 14/80 M.G. Six, Kimber modified a Morris Six, and designed a new chassis and a cylinder block that took twin carburettors and incorporated them into his new car. The car was powered with a six-cylinder, inline engine with chain-driven overhead camshafts. They produced about 60 bph and could achieve a top speed of 80 mph—which is where the 80 in the name originated. He also designed a beautiful new radiator grille for the 14/80, and this grille design was so popular that it was used on M.G. cars for more than 25 years. The grille featured vertical standing slats and a vertical center bar and the headlights were set higher.
The 14/80 Mark I and Mark II models were available in a variety of styles such as two- and four-door models, two- and four-seater cars, and both closed and touring cars. The Mark I was built from 1928 to 1931 and about 501 were built. The Mark II was built from 1929 and about 236 were built. Kimber also built a racing version in 1930 which was referred to as the Mark III, the 18/80 Tigress, or the 18/100. The engine was rated at 80 hp and only five were produced.
In case you were wondering what bph stands for, it is a measure of horsepower and here is a link to explain the difference between hp and bph. http://www.differencebetween.net/technology/difference-between-hp-and-bhp/
Article sources: https://en.wikipedia.org/wiki/MG_Cars
Great Marques M.G., by Chris Harvey, 1983
MG Past & Present, by Rivers Fletcher, 1985
MG by McComb, by F. Wilson McComb, Revised Edition by Jonathan Wood, 2004
Great videos about the MG cars and history on the MG Cars Channel by Shelburne Films https://www.youtube.com/channel/UCFApx5pUaAkNam6U1pn_ZEQ