pillar box
noun1
Ireland, UK A free-standing item of street furniture in the form of a short, red pillar (green in the Irish Republic) with a slot for posting letters.
- We were over the border here, into Northern Ireland, and the post office had a very English atmosphere. It was pleasant, too, much as we enjoyed the hospitality of the Republic, to be buying stamps with the Queen's head on them, and to be posting our cards in a red pillar-box, instead of a green one.1955 June, Rev. A. W. V. Mace, “An Irish Journey—2”, in Railway Magazine, page 393: