Originally Posted by seely
Actually thats not correct. I had a OS3 with the SN on the headtube, as did all Paramount OS's I have encountered, as well as some others. In fact, I am 99% certain that the bike in the pic is a Paramount OS series frame. I had one and it was absolutely identical in all details. Nice frame, very nice quality. The Tange dropouts are consistent too.
My Waterford built Paramount OS has the serial number on the BB. Perhaps the macihine built Japanese bikes had SN on the headtube.