The cars seen in the Morgan works appear to be Hudson or Hudson Essex.
I’m less sure of the identity of the car in the advertisement but as Morgan were also associated with bodies for Studebaker in the early 1920s it could be one of these as it does not appear to be a Hudson. I understand that Morgan also provided bodies for Renaults but it definitely isn’t one of those either.
Hudson in the 1920`s was in the U.S. the third largest car maker behind Ford and Chevrolet. They had factories in Canada, Belgium and England so the picture caption above could be right in saying the chassis were imported from America.
The Morgan carriage co. must have been very big in their time if they coach built onto chassis from Germany, France and the U.S.
Nice to get some input on what was to me a puzzle.