SOURCE: BBC (12-30-09)
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.
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.