NOT Paddy Roberts, this has also been dicussed. Brimstone says he got it from the author, a guy (student?) whom he has since been unable to trace, and who had more songs in similar vein. So his words would be the definitive ones.

Some differences in words:

First Verse
Although I loved this pretty fair maid, she loved a Portuguese

Quick pronounced Queek (in humorous manner), to rhyme with Speak

Last Verse
Thirty Years inside, not thirtyfive