Séamus Mallon famously described the Belfast Agreement as "Sunningdale for slow learners". The publication of British and Irish State papers from 1974 shows just how much there was to learn from the traumatic events of that year for Ireland's relations with Britain, power-sharing in Northern Ireland and North-South relations in Ireland.
That the papers should be opened just at the moment when an agreement between the Democratic Unionist Party and Sinn Féin has looked within grasp, underlines the continuing importance of the lessons learned from the failure of the Sunningdale Agreement, which was concluded on December 9th, 1973.
The new Northern Ireland Executive took office on January 1st, 1974, but was immediately embroiled in political controversy and contestation. Within a week Brian Faulkner had resigned as leader of the Ulster Unionist Party following a vote of no confidence by its Council. While he still held a majority in the parliamentary party, ratification of the agreement was continually delayed amid argument over the constitutional and political significance of the Council of Ireland.
Unionists saw the council as a Trojan Horse for Irish unity, as the Government's commitment to the principle of consent was obscured by media comment and legal challenge. Continuing violence by the Provisional IRA reinforced demands for stronger action against them. The Ulster Workers' Council built up its organisation towards a strike against the Executive in May. This was bolstered by a sweeping victory for anti-agreement candidates in the March general election, which saw Harold Wilson replace Edward Heath as Prime Minister in London.
The papers reveal that these enduring elements of the Northern Ireland crisis - power-sharing between the two communities, consent for Irish unity, the Irish dimension, British-Irish co-operation, IRA violence, loyalist mobilisation and electoral volatility - emerged in that eventful year. They were overlaid by Britain's intense intelligence and security involvement in Ireland. And they provoked a searching investigation by both governments of alternatives to the agreement should it fail, including the option of British withdrawal from Northern Ireland. After the Executive collapsed during the UWC strike in May 1974, the governments came to terms with the consequences of failure, laying the groundwork for more than two decades of direct rule. It was not until the mid 1990s that the elements which emerged in 1974 were brought back into full political engagement. They have yet to be fully implemented.
Historians have much to learn from these papers about the dynamics of this fateful year, but its lessons are still relevant politically as well. Despite astonishing progress in bringing its antagonists together in negotiations, one final element - trust - has yet to be established between them. Putting it in place will take risk and experience in equal measure.