Pride in Eire

Taken for DDW's March vocab challenge: rariora (rare collector's items such as books).

In a charity/vintage shop window, this vintage book is inkpad-stamped with a price tag of 10 1/2 d, and the phrase "Pride in Eire". I don't know the meaning or history of such a stamp. I've never seen it before. Perhaps it was an organised campaign, or perhaps just a personal show of support for the Republic from the bookseller at the time.