The Charatan Trafalgar (71 X) is an old one. The ones from the 70s were stamped either 171X or 371X depending on the group 1 or group 3 size, (the X being for a saddle mouthpiece). I think that this pipe was repaired at one time by Charatan (new mouthpiece) and during the frazing process the original stamping faded out but not completely. The person who finished the pipe noticed this and tried to re-stamp over it. Unfortunately, over the years, the original stamp die had been replaced (the single stamp die for Charatan's Make over London, England)and the new die's size was marginally larger. Anyway, that is my explanantion.