Bayliss, Thomas & Co. was founded in Coventry in 1874 to make bicycles under the name Excelsior. Motorcycles followed in 1896 and long outlasted the cars. In 1913 they made the world’s largest single-cylinder motorcycle engine, displacing 850cc. A new company was formed in April 1920 in Birmingham called Excelsior Motor Co. Ltd., and a car was planned. As there was already the well-known Belgian Excelsior car they used the original name Bay-liss-Thomas. It was a conventional light car powered by a 1498cc 4-cylinder Coventry Simplex engine, with their own 3 speed gearbox. In addition to the usual open 2 and 4 seater bodies, they offered a sliding door saloon made by Bowden of brake fame, and a doorless aluminium-bodied long-tailed sports model.
The 10.8 was soon joined by the 8.9hp Junior, powered by a 1074cc engine said to have been made in-house, but probably a Meadows unit. The 3 speed gearbox was also by Meadows and the worm rear axle by Wrigley. From 1924 they turned exclusively to Meadows for their engines, using several sizes of both side-valve and ohv units from the 1247cc 9.8 to the 1795cc 13/30. Only the latter had a 4-speed gearbox, but all had Moss spiral bevel rear axles. Front-wheel brakes were adopted in 1927. About 500 Meadow engines were supplied and in the mid 1920s the factory had a capacity of 40 cars a week, though they never achieved this figure. The Bayliss-Thomas was listed up to 1931, but production probably did not last beyond 1929. It is thought that about 1000 cars were made altogether. Excelsior motorcycles were made up to 1964, when the company name was Excelsior-Britax, makers of seat belts and other components.