Found new owner
In the beginning Dunhill created Bruyere. And several years (1910-1917) it was the single brand made by the company of a firm and dense Calabrian briar. And though pre WWII "bruyeres" were marked just by a letter "A" instead of model (or Ao like in this case), the Bruyere series is the one of the oldest long-livers not only in the Dunhill family, but also among all pipes in general. A sound Dunhill billiard sitter pipe with a very unusual stem construction (Vernon system) from 1933!
The pipe markings are "DUNHILL \ LONDON", "Ao", "MADE IN ENGLAND 13", "US.PAT. 1861910/32" (hardly visible), "T35". The length is 13.1 cm (5.16"), bowl's height is 4.3 cm (1.69"). External diameter of the bowl is 3.3 cm (1.3"), internal diameter is 1.9 cm (0.75"). The depth is 3.8 cm (1.5") and this pipe weights 30 gr. Briar, vulcanite stem, proprietary air cooler. The chamber has been protected with a break-in coat.