Have you contacted Westley Richards for more information? Guns for export from Britain are required by law to be 'In Proof'. Nitro Proof here only became compulsory from 1925; prior to that it was optional. Unusual in that it doesn't cock like a convention Anson & Deeley action to say that it was a Westley Richards development. Any Patent information on the gun? Interesting! Lagopus.....