Now we're faced with a pretty conundrum: did Séamus MacManus write the song or adapt it from a traditional version; or did traditional singers adapt, as they will, Séamus MacManus. The placenames in the version posted by Mary Conway are right for the area - Sillies is more usually given as Sillees; the river rises in Belmore Forest, flows past Boho and through the Moss Lough, there joining another tributary that goes through Derrygonnelly and, circuitously, joining the Erne at Enniskillen. The puzzle for me is in MacManus' using the spelling Boe. Phonetic? or is it a way of avoiding all but initiates giving Boho two syllables.

OK - I'll print the two versions and compare them with all the care known to man and look up all the places given by S MacM - are they all real or are some imagined? Watch this, or rather, later spaces.