Most Purdey .369s were re chambered to the .375 Flanged by owners who could not get or didn't like the original ammunition.

My info from Purdey is that only 72 .369 were made prior to being discontinued in the early '70s.

I do not know how many have been made recently nor do I know of how many .375 were made but I would guess the number is quite small for the older guns as well as the newer ones.

Good Luck on finding one but be aware that if it has been re chambered the value is substantially less than the .369 in equal nick.