Interesting question. Obviously it was only done for the American market. Have to look into it, but I'd say somewhere around the late seventies they probably stopped using it. The Marque Grand Luxe hats don't have it, but they weren't exclusieve for the American market, I think. Have to look at some more modern American market hats to be sure.Do you know when the “Original House” markings stopped? Maybe @steur or @Daniele Tanto can assist with this.