Tributes have been paid to businessman Sir George Quigley who died yesterday.
The former civil servant went on to become the chairman of Ulster Bank before he was called as an independent witness as the Ulster Defence Association (UDA) decommissioned its weapons.
It is believed he fell ill during morning worship at Helen's Bay Presbyterian Church.
First Minister Peter Robinson and Deputy First Minister Martin McGuinness said in a joint statement: "We offer our sincere and heartfelt sympathies to his family, friends and colleagues. they .
"We were fortunate to meet Sir George on many occasions.
"His contribution to public service and the business sector was highly regarded and he played an important role in developing networks within our community that sought to seek a better understanding of each other's views.
"He was a strong advocate of mutual respect in building a cohesive and equal society."
Sir George graduated with a first-class honours degree and PhD from Queen's University, Belfast, and during his career in the civil service was permanent secretary in several departments including manpower, commerce and finance.
He later became chairman of Ulster Bank, where he remained until 2001, and served for 10 years as a non-executive director on the main board of NatWest.
Elsewhere his roles in public life have included chairman of the NI Economic Council and the Royal Group of Hospitals and he conducted a review of the Parades Commission.
In the Republic he had been president of the Economic and Social Research Institute and chairman of the board of the Institute of British-Irish Studies in University College Dublin.
Sinn Fein president Gerry Adams said he was shocked at the news of his death.
"George was for many years a senior civil servant and then business leader," said Mr Adams.
"He was an experienced economist and was a long-time advocate of the all-Ireland economy.
"Last year he participated in a Sinn Fein conference in Derry on the issue of uniting Ireland.
"On my own behalf and that of Sinn Fein I want to extend my condolences to his family, friends and colleagues."