As in did they ever fear a communist/Soviet-sympathetic government in Dublin? Did the British have any contingency plans for such a possibility?
As a followup, I found this poster on twitter, which seems to be an example of exactly what OP is asking about, but I'd love to get more historical context for why this poster was created and how people thought 1970s US-Cuba relations were similar to those of the UK-Ireland.
I touched briefly on this, but more could always be said about it. Or if you have any follow up questions, I'll try my best to answer them.