Sean MacDiarmid makes an equally fleeting appearance in a song by Peadar Kearney called A Row in a Town.[Kearney was the writer of Amhrán na bhFiann, and the brother of Kathleen who married Stephen Behan and gave birth to all the obvious.]

The relevant verse is:

God rest gallant Pearse and his comrades who died:
Tom Clarke, McDonagh, MacDiarmid, McBride.
And here's to Sean Heuston who gave one hurrah
And faced the machine guns for Erin Go Bragh.