Here is an email from Holland & Holland regarding my shot and regulated by Holland and Holland 12 gauge.
"Dear Mr. Bates,
Thank you for your email.
We do provide a historical research service for a charge of Ł30.00 but having checked our records on your shotgun, the record is in fact blank and so would be unable to provide you with any further information.
However I can confirm that your gun was finished in 1967. Your shotgun was one of a number of Boxlock Ejector's that Holland & Holland commissioned to be built through the Birmingham gun trade as it was cheaper to produce and thus cheaper to retail. When the guns were nearing completion they were sent to the Holland & Holland factory for final test shooting, regulating and finishing. Therefore since they were not true Holland & Holland shotguns built entirely at the factory we engraved "H&H" on the sideplates and not the full "Holland & Holland" name and the model name; "Shot & Regulated" engraved on the barrels.
As mentioned these were made through the Birmingham gun trade with a large number, as you correctly pointed out, being made by Webley & Scott and coincidentally your gun was actually made at the Webley & Scott factory.
I hope this helps.
Best regards,
Andrew Ambrose
For Holland & Holland"
There is some question when it comes how close to finished the shotgun were when shipped for regulation.