"All this being said, I think George is asking about the dating of the pipe in the OP."
Mr. Loring's "SHELL FINISH PATENT NOMENCLATURE USAGE" chart (Ref. Pages 58 and 59 of his aforementioned book) indicates that this particular combination of U.S. Patent Numbers, combined with the "DUNHILL'S "SHELL" MADE IN ENGLAND" stamping (with the latter all on the same line), was used from 1927 through 1933. Earlier I stated that this indicated only 1927, and that was wrong.
Mr. Loring's "SHELL FINISH PATENT NOMENCLATURE USAGE" chart (Ref. Pages 58 and 59 of his aforementioned book) indicates that this particular combination of U.S. Patent Numbers, combined with the "DUNHILL'S "SHELL" MADE IN ENGLAND" stamping (with the latter all on the same line), was used from 1927 through 1933. Earlier I stated that this indicated only 1927, and that was wrong.