Found new owner
A "special edition" of one of the most successful GBD Prehistoric series. The designation "Collector" (along with "Conquest" and "Colossus") served for marking of especially large pipes. At the same time the name Collector is really justified: pipe smokers from many countries (and furthermore refined collectors) appreciate and extol such convincingly large pipes. Just recall Lane era Charatan's "large" and "extra large" pipes made first of all for USA market :-) So there's definitely a collectable and valuable pre-Comoy's GBD pipe (made before 1980)!
The pipe markings are "Collector \ (GBD)", "LONDON ENGLAND \ 9557 \ Prehistoric". The length is 16.2 cm (6.38"), bowl's height is 5.7 cm (2.24"). External diameter of the bowl is 4.2 cm (1.65"), internal diameter is 2.2 cm (0.87"). The depth is 4.5 cm (1.77") and this pipe weights 48 gr. Briar, perspex stem, no filter. The chamber has been protected with a break-in coat.