Many thanks to Brian Hanly and others for supplying the following info about the poster
from November 1934, a Republican Congress protest at a rally addressed by Eoin O’Duffy in the Mansion House. The Blueshirts had actually split by this stage so it was actually a ‘Fine-Gael’ splinter event! Congress propaganda against the Blueshirts tended to use both anti-fascist and Civil War motifs; so they would have accused the Blueshirts of being pro-British or pro-Empire. (In actual fact the Blueshirts tended to be the most nationalist/Michael Collins types within Fine Gael and had plenty of 1916-21 veterans among their officers). Anyway Frank Ryan and Peadar O’Donnell spoke at this I think.
77 was the number of Republican prisoners executed by the government during the Civil War.