Sean Donlon, the Secretary General of the State Department, went on to say that « Reagan`s intervention was crucial and made possible by Tip. »  Michael Lillis, Deputy Secretary General of the Department of Foreign Affairs from 1983 to 1985, also stated that « O`Neill has been very active and effective in mobilizing the President. And there is no doubt that Reagan`s regular references in his interaction with Thatcher helped us a lot.  David Hanson died on November 15, 1985 at 10:20 a.m. Three hours later, Garret FitzGerald and Margaret Thatcher signed the Anglo-Irish Agreement at Hillsborough, just over 40 miles away. Such an attempt had already been made in 1973. In Northern Ireland, a power-sharing executive of Irish nationalists and trade unionists was established and Prime Minister Liam Cosgrave participated in discussions with British Prime Minister Edward Heath, which resulted in the Sunningdale Agreement. This agreement recognised that Northern Ireland`s relations with Great Britain could not be changed without the agreement of the majority of its population and provided for the creation of a Council of Ireland composed of both members of the D`il (the lower chamber of the Irish legislature) and the Northern Ireland Assembly. This agreement failed in May 1974 because of a general strike inspired by Unionist opponents of power-sharing. But by the end of November 1985, the Oireachtas had approved it. More importantly, the British House of Commons was also elected with 473 MPs against 47, which was certainly an indication of the « other island` perspective ». The agreement was negotiated as a step towards easing long-standing tensions between Britain and Ireland over Northern Ireland, although trade unionists in Northern Ireland (who were in favour of the UK`s continued existence) strongly opposed their southern neighbour having a say on domestic policy issues. Many political leaders – including Thatcher, who had been strongly committed to British sovereignty in Northern Ireland – were convinced that a solution to years of religious violence in Northern Ireland could only be found through a comprehensive agreement. November 17, 1985 in Hillsborough, Co.
Down, signed by Margaret Thatcher and Irish Prime Minister Garret FitzGerald. The agreement should promote reconciliation in Northern Ireland and cooperation between the British and Irish governments. The Ulster Unionists saw it as a form of common authority, and in 1985/6 they waged a fierce opposition campaign. Sinn Féin and the Provisional IRA were also hostile to the agreement and believed that the agreement recognises and legitimizes the State of Northern Ireland. No change in Northern Ireland`s status without their consent. The legitimacy of the position of trade unionists was recognized by the Republic in a formal international agreement. By-elections called after the resignation of the Unionists did not give voters a clear choice because of the reluctance of other parties to challenge them. No Unionist candidate rejected another, while the SDLP and Sinn Féin ran for only the four seats, where the majority of votes for nationalist candidates had been voted on in previous elections.
The SDLP has rejected an offer by Sinn Féin to enter into a nationalist electoral pact against the Unionist electoral pact.  The SDLP was given the seat of Newry and Armagh.