Love that! I think huntertrw is correct, the only other thing I might add is the lack of date stamps during WWII 1941-45. From John Loring, see here,Duke Street Irregulars
The above quote made me think Loring was pretty unequivocal but then too we all know the pipe world is anything but exacting! Even Dunhill.DUNHILL SHELL MADE IN ENGLAND
PATENT No 1341418/20
Since the usage of this particular stamping tool was only during the war, the stamp in and of itself serves to date a pipe to the handful of war years
Calling the Duke Street Irregulars