Here's from another thread where Andrea answered it:

The code stamped on the underside of the saddle is the date of production. Since a few decades you find a 3 digit sequence: "number", "letter", "number". For example 9C2:
-"9" and "2" stand for 1992
-"C" is the month and as it is the 3rd letter of the alphabet it means March

Don't ask me how my English colleagues and forefathers came up with this. I guess it was a way to kind of hide the date of production.

Andrea
BROOKS ENGLAND LTD.

I think that pertains to the code stamped onto the metal cantel plate though. I'm not sure about the stamps on the leather.