A flea and a fly in a flue

Original Text: 
The Penguin Book of Limericks, ed. E. O. Parrott (Allen Lane, 1983): 256.
2Were imprisoned, so what could they do?
3     Said the fly: `Let us flee'
4     Said the flea: `Let us fly!'
5So they flew through a flaw in the flue.

Notes

1] flue: a chimney or boiler pipe that releases flames and hot gases to the air but that, in mild weather, might have been stopped up? Back to Line
RPO poem Editors: 
Ian Lancashire
RPO Edition: 
RPO 1999.
Rhyme: 
Form: