Hi FoM,
I wrote to a film company in Denmark, as I noticed the name of the distributor on your poster, in the lower left (Gloria). I received a reply this morning, which can maybe help date your Quiet Man poster a little better. The distributor, Gloria Film, was started in 1993 or '94, and they were only operating until 2004.
As another side note, The Quiet Man premiered on Danish TV on November 27, 1991.