Jaguar was founded in 1922 by William Lyons and William Walmsley as the Swallow Sidecar Company, it later changed it's name to SS Cars and stayed that way until after the second World War when the name SS cars became a bit of an embarrasing name given the role of the German SS. The name Jaguar was chosen as this had appeared on a SS model back in 1935.
Jaguar merged with a number of other British car manufacturers that went on to emerge as British Leyland in the 1970s