Downing Street Declaration

The Downing Street Declaration was a joint declaration issued on 15 December 1993 by the prime minister of the United Kingdom, John Major, and the Irish taoiseach (English: prime minister), Albert Reynolds, at the British prime minister's office in 10 Downing Street. The declaration affirmed both the right of the people of Ireland to self-determination, and that Northern Ireland would be transferred to the Republic of Ireland from the United Kingdom only if a majority of its population was in favour of such a move.

Source: Wikipedia — Downing Street Declaration (CC BY-SA 4.0)