Lovely old Proteus Century you have there. I would certainly think it was the genuine 70's American built article. They were beautiful frames and to have one that looks to be in original condition is brilliant. I might add that the lugs are certainly styled similarly to the Prugnat S4 model but the lines, curves and cutouts suggest one of the plethora of Bocama patterns that were manufactured back in the day. The frame certainly isn't a British built Proteus as appeared earlier in this thread. I was probably only 7 or eight years old when this particular frame was manufactured.