The peer, also known as Dr Edward Haughey, 70, was chairman of Norbrook, the largest privately-owned pharmaceutical company in the world.
He was killed along with three other people - two pilots and a man from Mayobridge in County Down - when a helicopter came down in thick fog in a field in Gillingham, near Beccles, at 7.30pm.
According to the Register of Lords’ interests, Lord Ballyedmond owned Gillingham Hall, a stately home near the crash site. The register also states that he was a controlling shareholder of Haughey Airports Limited, an airport operator, and Haughey Air Limited, an airport transport company.
A life peer with a seat in the House of Lords, first on behalf of the Ulster Unionist Party before switching to the Conservative Party, he also owned Ballyedmond Castle in Rosstrevor, Co Down, and Corby Castle in Cumbria, as well as a property in Belgrave Square, London.
His wealth was estimated to be in excess of £400 million, making him one of the wealthiest men in Ireland.
Karen McKevitt, a Northern Ireland Assembly Member representing South Down, paid tribute to the pharmaceuticals entrepreneur and politician.
She said: “It is feared that there are other casualties from the South Down area.
“It is very, very shocking news for everyone here. Edward Haughey is the biggest employer in the area, he has done a tremendous amount of work for local charities and schools, and is very, very well known.
“It is his employees who have the greatest respect for him in the area.
“The whole of Northern Ireland will be devastated by this news. It is very raw.
“I do know that the Police Service of Northern Ireland have been contacted but we haven’t been given any details.”
The man who died with him was named locally as Declan Small, 42, a foreman who worked for Lord Ballyedmond. He came from Mayobridge, Co Down.
Lord Ballyedmond was born in 1944 in Dundalk, Co Louth, and began his pharmaceutical career in the US in the 1960s selling animal drugs.
He returned to Newry in Co Down to set up his own business and founded Norbrook more than 40 years ago.
The company proved to be a highly innovative business and increased its margins by making many of the raw ingredients used in its medicines.
He expanded into Africa and is reportedly one of the largest veterinarian suppliers on the continent.
Two of his companies, Norbrook Laboratories and Norbrook Holdings, employ 1,300 people worldwide, 1,000 of them in Northern Ireland.
He also owned an air travel business, and at one stage the lease of Carlisle Airport in Cumbria, which he sold in 2008.
Apart from Northern Ireland and London, he had a house in Dublin’s expensive Fitzwilliam Square, close to the city centre, owned two islands on Lake Victoria in Uganda, and was a collector of rare plants and trees.
In July 2008 he was made an honorary doctor of science by the University of Ulster.
He was married with two sons and a daughter. He was made a life peer as Baron Ballyedmond of Mourne.
Stormont enterprise minister Arlene Foster said: “Without doubt, Lord Ballyedmond was one of Northern Ireland’s most successful entrepreneurs, and he was known for his leadership, integrity and global vision.
“One-of-a-kind and a self-made businessman, he was both highly regarded and widely respected by all those who knew him.
“Norbrook Laboratories currently exports to more than 120 countries worldwide and Lord Ballyedmond worked tirelessly to promote Northern Ireland as an investment location.
“Not only has he made a huge contribution to the local economy but Lord Ballyedmond also devoted much of his time to charitable works and this is to be highly commended.”
James Tuttle, 41, from nearby Geldeston, saw the helicopter come down.
He said: “We used to see him coming and going in his helicopter from our back garden all the time.
“At about 7pm we noticed the helicopter coming in very low and at an unusual 45-degree angle.
“We didn’t hear any bang or explosion - it just seemed to be flying in a strange way.
“The fog wasn’t that bad at the time - just patchy - it only got worse about an hour after the crash happened.”
Jim Blair, from Gillingham, said Lord Ballyedmond had been renovating the property for several years.
“We understood he was due to complete the work in April,” he said.
“He’s spent a lot of money on it and people in the area were curious about what he was doing.”
Asked about reports that Lord Ballyedmond was taking legal action against AgustaWestland in relation to possible safety defects with his AW139 VIP helicopter, a spokesman for the company said it was investigating the case.
Speaking from the company’s office in Italy, he said: “We cannot comment now because we need to make internal checks to establish exactly what the situation is.
“We cannot yet comment on this accident because there is an investigation pending and there could be many causes, be them technical or due to human error.
“Obviously we are very much regretful of what happened and will support the ongoing investigation in any possible way.”