I don't know if that is altogether true. Don't Bentley and Rolls Royce still use names?
Names were used almost exclusivelyway back in the 1930's for some makes - MG spring to mind with Magna, Magnette, & Midget, but they did have a letter & number that defined say, a saloon variant from an open sports model etc (e.g. The 1933 MG Midget range was known as the J-type Midget - J1 being a four seat variant, J2 being the two seater, a J3 was a supercharged racing two seater, and a J4 was an out and out racer with a lighter body and bigger supercharger), but they were all still known as the Midget.
Riley, Wolsely, Austin and Morris all seemed to use a mix of both names and numbers.
It is an interesting motoring question though!