Found new owner
That's a very rare sample of the Dunhill Shell Briar pipes stamped with a letter shape code instead of a number. Such codes were used at times prior to 1976 (according to Pipephil) and the shape "P" corresponds to "1/2 bent bulldog". A unique collector’s finding!
The pipe markings are "P F/T", "DUNHILL \ SHELL BRIAR", MADE IN \ ENGLAND 9", "(4) S" (hardly visible). The length is 14.4 cm (5.67"), bowl's height is 4.1 cm (1.61"). External diameter of the bowl is 4.5 cm (1.77"), internal diameter is 2.1 cm (0.83"). The depth is 3.2 cm (1.26") and this pipe weights 44 gr. Briar, vulcanite stem, no filter. The chamber has been protected with a break-in coat. The rim is not ideally flat but this doesn't affect smoking qualities of course, rather it adds a unique charm to this exciting pipe!