When you say it is a “standard sporterized No.1 “, what does that mean? Is it an ex-service rifle (with government markings and date) that has been converted to a sporter? Or was it built as a sporter (with commercial markings)?
If the former, it might have been fitted with a barrel by/from Lincoln Jeffries. If the latter (which is more likely), it was a BSA commercial sporter retailed by Lincoln Jeffries.
A few pics of the markings will tell us. Or if you can describe the markings.
Would love to know. To those of us who study the
British
gun trade and its history, the Jeffries connection is a plus. It’s a piece of history. Jeffries (the company) is best known for air guns (and their connection to BSA) but they produced shotguns and rifles too, having been in Birmingham since at least the 1870s. Lincoln Jeffries’ great-grandsons carry on the business today.