The Anglo Irish Agreement was signed in 1985
A senior Irish civil servant who was involved in the talks leading to the 1985 Anglo Irish Agreement has died.
Dermot Nally, 82, who served under five taoiseachs, died suddenly in St Vincent's Hospital in Dublin.
As well as leading Irish officials in the Anglo Irish deal talks he was also involved in the negotiations preceding the 1993 Downing Street Declaration.
Taoiseach Brian Cowen said his death will be "noted with regret" by all those he worked with over the years.
Mr Cowen said Mr Nally would be particularly remembered for his contribution in relation to Northern Ireland.
He offered his sympathy and that of the government to Mr Nally's family.
Mr Nally is survived by his wife, Joan, brother Fergal, sister Sheila, son Brian and daughters Ailbhe, Maura, Sheila and Catriona.
When it was signed the Anglo Irish Agreement was the most important development in British-Irish relations since the 1920s and was aimed at helping establish a devolved administration.
The British and Irish Governments, led by Margaret Thatcher and Garrett FitzGerald, respectively, confirmed that there would be no change in the status of Northern Ireland without the consent of a majority of its citizens.
However, it also gave the Republic an advisory role on Northern Ireland's governance and was bitterly opposed by unionists as a betrayal and the first step towards a united Ireland.
Just a week after the Agreement was signed, 100,000 unionists gathered to demonstrate at Belfast City Hall.
On 17 December all 15 Unionist MPs resigned from their seats forcing by-elections to highlight their opposition to the deal.
A "day of action" was declared 3 March, 1986 which closed down much of Northern Ireland's industry and commerce.
The 1993 Downing Street Declaration saw the UK Prime Minister John Major and Irish Taoiseach Albert Reynolds deliver the terms they hoped would lead to peace and multi-party talks.
It argued for self-determination on the basis of consensus for all the people of Ireland.
It argued that any agreement had to be based on the right of people on both parts of the island to "exercise the right of self determination on the basis of consent freely and concurrently given, North and South, to bring about a united Ireland if that is their wish".