The story which I heard many years ago regarding Glasgow Celtic is that one of the original founders of the team gave a press conference. He called the team "Glasgow Keltic" but apparently the assembled reporters insisted on using the word "Seltic" and the name stuck. Reminds me of the tale about a certain actor (no longer with us) who was approached by a woman who asked him if "he were a Selt." "No", he replied, "No more than you are a sunt." Apocryphal perhaps?