One of the most interesting aspects of Eire’s rather odd neutrality. There was, strictly speaking, no need to make the signs distinct from one another by numbering them. All that was required was the national name to discourage overflight.
If you had a chart with the numbers on them, as the RAF did, it wouldn’t simply tell you that you were over Eire, but also exactly where over Eire you were.....
DeV and Churchill’s public spat in 1945 concealed a great deal of subtle co-operation.