I think this song has been recreated in different miltary circles for a long time, and the IRA version predates Behan. For comparison, the chorus from the Waterson's English version:

Hurrah for the khaki and the blue
Helmets glittering in the sun
Bayonets flash like lightning
To the beating of the miltary drum
And no more I will go harvesting
Or gathering the golden corn
Coa I've got the good king's shilling
And I'm off tomorrow morn