More on Tom Tug from Infoplease:

• Tom Tug - Tom Tug A waterman. In allusion to the tug or boat so called, or to tugging at the oars. Source: ...
• Biddy - Biddy (i.e. Bridget). A generic name for an Irish servant-maid, as Mike is for an Irish labourer. ...
• Tom - Tom Between “Tom” and “Jack” there is a vast difference. “Jack” ...
• Dictionary of Phrase and Fable: T - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "T"