Sorcha, that prompted me to get the dictionary out. From "The Chambers Dictionary":

bodge (colloq) variant of botch (vt and vi); (shakeps vi) prob varient of budge. n(colloq) a piece of poor or clumsy workmanship; a clumsy worker (also bodger).

The dictionary also gives Mark Clark's definition of "bodger" as a separate entry and notes [origin uncertain].

Jon