the name has been spelled Frotesham, Frodesham, Fradsham, Frandsham, Frodisham, Ffradsam, Ffradsham and Frodsham.
Norman surnames are characterized by a multitude of spelling variations. The frequent changes in surnames are largely due to the fact that the Old and Middle English languages lacked definite spelling rules. Since medieval scribes and church officials recorded names as they sounded, rather than adhering to any specific spelling rules. Hence all the different spellings of Frodsham.