Shortly afterwards , Robinson resigned from the party in protest at the Anglo-Irish Agreement , she said that unionist politicians in Northern Ireland should have been consulted as part of the deal . Shortly afterwards , Robinson resigned from the party in protest at the Anglo-Irish Agreement that the coalition under Garret FitzGerald had signed with the British Government of Margaret Thatcher . Robinson argued that unionist politicians in Northern Ireland should have been consulted as part of the deal , despite their reluctance to share power .