Hiya Leadbelly!
The Dominic Behan lyrics from his book "Ireland Sings" has "speech" rather than "leeks" (but everyone sings "leeks").
Den's text is the same as in the book, but I've always heard it sung: "long may it flow between England and me".

The book states that the tune is the old melody of "'S Fágaimid Siúd Mar Atá Sé",
and that Dominic got the title line from his mother from a song that a friend Mick Byrne wrote.

"gradh geal mo croide" (which should be "grá geal mo chroí" in modern Irish) is pronounced "graw gyall muh hree".

MvG, Gulliver