Thatcher hoped to conclude a bilateral agreement with Dublin that would strengthen security while recognising the „Irish dimension“: the historical and cultural relations between the Republic and Northern Ireland. By recognising these Irish ties and granting Dublin an advisory role in Northern Ireland, without relinquishing British sovereignty, Thatcher hoped to attract moderate nationalists to the six counties. The deal was rejected by Republicans because it confirmed Northern Ireland`s status as a member of the United Kingdom. The Commissional Irish Republican Army (IRA) continued its violent campaign and did not support the deal. Sinn Féin President Gerry Adams denounced the deal: „formal recognition of the division of Ireland. [is] a disaster for the nationalist cause. [it] far outweighs the powerless advisory role that has been assigned to Dublin. [42] On the other hand, the IRA and Sinn Féin claimed that the concessions made by Britain were the result of its armed campaign which gave political recognition to the SDLP. [43] Brian Feeney of the SDLP proposed that the 1986 agreement speed up Sinn Féin`s decision to abandon the abstention of the Republic Oireachtas. [44] What happened next was a decade of lost years and drifted towards unionism. Molyneaux and Paisley sulked and groaned, clinging to the idea that the deal was going to unravel on its own. No new strategy or policy was proposed, leading to a situation in which Peter Robinson and David Trimble thought Northern Ireland was in danger of falling out of the „window“.

One of them, Enoch Powell, accused Mrs Thatcher of „treason“ the day before the deal was signed. The British House of Commons voted in favour of a request for approval of the agreement by a majority of 426 (473 in favour and 47 against, the largest majority during Thatcher`s term). The majority of the Conservative Party voted in favour (although there were a few Unionist MPs within the party who opposed it), as well as the Labour Party and the Liberal Alliance-SDP. Of Northern Ireland`s main parties, only the Nationalist Democratic and Labour Party (SDLP) and the Inter-Community Alliance supported the deal. The admission is particularly striking because dr. Paisley in 1987, just two years after the deal, publicly repressed peter Robinson, then deputy — which led to Mr Robinson`s resignation as an MP for some time – after he and senior UUP officials drafted a report whose central conclusion resembled that of Dr Paisley in 1992. He then expressed concern that the agreement threatened Irish neutrality and risked forcing the Republic of Ireland to accept the British presence in Northern Ireland. Former cabinet minister Tony Benn and Ken Livingstone, then chairman of the Greater London Council, also rejected the deal because they believed Britain should withdraw from Northern Ireland.

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