Irish postal stationery envelope with 6d imprint used at the domestic printed matter rate in December 1970
Digital photo taken by <a href="https://en.wikipedia.org/wiki/en:User:Ww2censor" class="extiw" title="w:en:User:Ww2censor">Ww2censor</a>, the author of the work
CC BY 3.0
<a href="https://en.wikipedia.org/wiki/en:Image:Stamp_Irl_6dpse.jpg" class="extiw" title="w:en:Image:Stamp Irl 6dpse.jpg">en.wikipedia.org</a>