Dunhill Patent Stamps and Dating

Dunhill patent stamps are the marks struck on the shank of a Dunhill pipe that help narrow its production year. On the brand's early pipes, one or two patent numbers sit atop the shank, alongside the brand name and a city line, and from the 1920s onward a small year code as well. Reading these three elements together narrows the production date, in most examples, to a few years, and in favorable cases to a single year.

The Patent Period

What collectors call the "patent period" covers the years during which the habit of stamping a patent number on the shank began and was later dropped; compilations give this range as roughly 1905–1954. Alfred Dunhill's first English patent related to a pipe was filed on 21 November 1904 and granted on 28 September 1905. The document concerns adding a windshield to the bowl, either permanently raised or removable and made of metal or asbestos; the aim was to protect burning tobacco from wind outdoors. Brand history notes that this pipe was developed especially with motorists in mind. Application number 25261 is the basis of the two-line DUNHILL'S over PATENT stamp struck on the shank. These first pipes appeared before Dunhill opened his tobacconist's shop on Duke Street in 1907. It is recounted that the stamp was dropped around 1910, once the brand moved into its own manufacturing and placed DUNHILL over DUKE ST. S.W.; the same records also say the earliest pipes were made of polished Algerian briar and produced in only two shape codes, "T" for billiard and "U" for bulldog.

Inner-Tube Patents

The aluminum inner tube (inner tube) fitted inside the shank is the brand's most prolific source of stamps. English patent 5861/12 was applied for on 8 March 1912 and granted on 6 March 1913; the text describes a removable, straight metal tube with both ends specially shaped. Pipes shipped to America used the American counterpart of the same invention: patent no. 1,130,806, filed 7 March 1913 and granted 9 March 1915, appears on the shank as PATENTED MARCH.9.15 or PAT.AMERICA 1915. English patent 116989/17, in the names of Alfred Dunhill and Thomas George Mandeville, was applied for on 26 September 1917 and published in 1918; its innovation was a flange holding the tube in the shank. From 1918 onward, examples begin appearing where the two numbers sit side by side on the same shank. Another marker of these dates is US patent no. 1,341,418, filed 14 October 1918 and granted 25 May 1920; it describes soaking the wood in oil, heat treatment, and sandblasting to bring out the grain, as a single production sequence.

Brand Stamp and Year Code

When the patent number alone doesn't give a narrow range, the shape of the brand stamp comes into play. The work most often begins from the roughest boundary: since the white dot the brand placed on the mouthpiece began being used in 1912, a pipe with a dot cannot be dated earlier than that. Shank wording shifted to DUNHILL over LONDON at the very end of autumn 1918; because sources give slightly different dates within a few weeks for the transition, the exact day is not certain. Through 1919 the curve and length of the two lines were recut several times, so the alignment of the letters may allow an estimate down to the month. In the same years, the tailed "D" letterform, and whether the "A" stamp is circled or not, is also taken to narrow the range to 1918–1924.

The year-code system was established in 1921. Right after the patent number, sometimes after the word ENGLAND, a small, underlined digit is struck. Compilations report that the digit 1 corresponds to 1921, 0 to 1930, and the numbers 11 through 14 to the years 1931–1934. According to the same records, since the system did not catch on in its first year, a pipe carrying the tailed "D" but no code is generally dated to 1921.

When the Stamp Can't Be Read

It is common for the factory to have skipped striking the code, or for the stamp to have been erased during polishing; in such cases secondary clues are turned to. The MADE IN ENGLAND wording is taken to be found mainly on pipes headed for export up to roughly 1926–1927, and the registration number struck on top of the mouthpiece is taken to have been used from the mid-1910s to the early 1930s. Contradictions between stamps are not unusual; for this reason it is recommended not to rely on a single detail but to look at everything marked on the shank together.