"With icy eye" was tempting to me, too, Jeri, but with how well the rest of the song (and others of Behan's I've heard) flow, that came off a bit clunky. I think ICI makes an awful lot of sense there.

I'm still not 100% confident on the line above that, but here's a revised attempt:

I had a friend who met his end, 'twas easy as a pie
He thought he let the shares he bought ascend -- you ought to lie!
Full of ICI, his broker couldn't quite see eye to eye
And now he's left a beggar in Throckmorton