.......
I may be confabulating this with something else, but my fried brain cells think they remember something about some Brooks saddles having a code _inked_ into the underside of the leather? Which often faded, or disappeared with Proofide applications. Does that ring any bells with anybody?
Actually, just found a BF post from '08, and evidently earlier saddles had ink stamps under the flaps, and the secret decoder ring was lost so nobody can decipher them any more, if they're still visible. After the flap stamping, they went to the cantle stamps.
my '73 Brooks Pro had that three letter stamp....
but... it also has the B73 stamped into the cantle piece....
as such, I don't think the three letter stamp is a date code for the saddle.
Steve in Peoria