This Warner Bros.logo is listed on Logopedia as being the logo used by Warner Bros. Pictures during 1923 - 1929. Note the same logo appears on The Maltese Falcon poster from 1931. It also appears on a number of 1930 Warner Bros. U.S. posters from 1930 that I have sighted. Another example of information appearing on Logopedia that isn't always factual. Nice poster by the way.