From a Usenet article by Norman HarrisonDunhill started to date code their pipes in 1960. After “Made in England” you may find a number (e.g.: 30). This means the pipe was manufactured in 1990 (1960 was 00, therefore 30 is 30 years after 1960 which is 1990 and so on). Pipes manufactured before that date (1960) may have to be dated by the style of logo etc).
|#||Group size of the pipe||#||Mouthpiece style||#||Shape|
|5||Largish||5||Quarter bent saddle||05||Dublin|
Take for example a pipe with the Code 4103.
This would be a Group 4 Billiard with tapered stem.