There should be a law that when posting a British rifle on the internet for sale that if you don't include a photo of the proof marks, the gun is free to the first caller. No 43049 should be 1955-57 or so, so yeah, it's from that early post-war period that the controversial guns came from. If the gun was proved in Brum (should have been), there will be a date code mark among the proof marks that will tell you the year that it was proved. London didn't start their date code until 1972. Let me know what the code is when you get it, and I'll give you the year.

Awfully plain gun for the price. Pay particularly close attention to how it functions when operated rapidly. The problem with the rebated rim of the .425 was poor quality guns, not the cartridge design.