I've only just registered in order to help another member with a greek-language question and stumbled upon yours, as well: of the cuff I'd say this is a poster from the '50s, when Cyprus was trying to become united with Greece. ΕΝΩΣΙΣ means UNION in Greek. In a nutshell, Digenis (George Grivas) was a Cypriot career army officer in the Greek Army, who eventually led the EOKA guerillas, Makarios was the Cypriot Archbishop and then Head of State of Cyprus, and Papandreou was the 1st of 3 Prime Ministers in Greece (his son and grandson) who started his career in the Lebanon & Cazerta conferences deciding the future of Greece when the Germans would eventually withdraw and who became PM in 1944.
Thank you Very much again!!! Great to see a new member helping out!!!
I talked to a Greek Friend here and showed him the poster, he came up with the same idea about the poster, however he thinks it is 60s or 70s.. I tend to think early 60s myself
you are right, this is from the early 60s; acc. to Wikipedia, Papandreou became PM again in 1964, but Cyprus had already become independent in 1960; Grivas visited Athens and then was sent to Cyprus in 1964.