This party, like some others in Quebec, never attempted to get the English-speaking vote, which went to the Quebec Liberal Party, and therefore were always know both inside and outside Quebec as the "Union Nationale".  So that is the name commonly used by English speakers in Canada.  The same with the PQ and ADQ.  The Quebec Liberal Party on the other hand which once had links to the Liberal Party of Canada is always referred to in English by English-speaking Canadians.