Tim,
I have seen many low grade Darnes with just a three digit serial number and always wondered about that. Prewar Halifax models always seem to be marked with just three numbers. I was told that a serial number wasn't really required by law until after the guns had been in production for 75 years or so, and the numbers just helped the gunmakers keep the parts from getting mixed.
One other note, at one time I owned a V20 two barrel set, which had a serial number that defied dating it-6 digit number if I recall. While having it worked on, Hervé pointed to the engravers name, "Bernaud", if I'm not mistaken, and said it was built before 1912-he knew that because Bernaud had died that year. But not too much before 1912, since he had worked up to his death, and the work closer to that year was not his best. This gun had engraving that was not his best!
Funny, but, true.
Best,
Ted
