Ireland - Slogan Postmark

I got a small cover from a dealer when I was in England in the middle of 1990s. It is a cover from Ireland. I like it because it has a clear and nice slogan postmark sending a message on donating kidney. The slogan postmark reads as "BE A KIDNEY DONOR". The cover was posted from Baile A'tha Cliath on August 26, 1985.