Businessman and politician with seats in both the Irish and British upper houses
Lord Ballyedmond, who has died aged 70 in a helicopter crash near his stately home on the Suffolk-Norfolk border, was a self-made multimillionaire whose business and political influence straddled both sides of the Irish Sea. He was the first person since the Marquess of Lansdowne in the 1920s to sit in both upper houses of the British and Irish parliaments, first as a senator in Dublin and later in the House of Lords.
Unlike other, brasher Irish entrepreneurs such as Ryanair's controversial chief executive, Michael O'Leary, the industrialist managed to maintain a low profile for someone who emerged as Northern Ireland's richest man. Edward (Eddie) Haughey valued his privacy to the extent that he once built a 12ft wall screening off his South Down home from the public, a move that put him in conflict with the county council. When, more than a decade ago, it ordered him to lower the wall by 4ft, he hinted that he might move his factory out of the region. The threatened legal action by the local authority was quietly withdrawn.
The centrepiece of Haughey's empire was the Norbrook Laboratories factory in Newry, Co Down, which employs 1,700 people and is visible from the Enterprise train when it stops at the town's railway station on the way to either Dublin or Belfast. Haughey founded the veterinary pharmaceuticals company in 1968, turning it into a global success story and bringing jobs to a region blighted for decades by unemployment and terrorism. While the South Down/South Armagh region became notorious for IRA activity, earning the nickname "bandit country" in the 70s, Haughey kept on quietly building up his business and becoming one of the wealthiest entrepreneurs on the island of Ireland.
He was adept at making friends on either side of the historic unionist-nationalist divide. Albert Reynolds, the taoiseach who helped coax the Provisional IRA to call a ceasefire in 1994, appointed Haughey to the Irish Seanad in the same year. Later Haughey was nominated to Dublin's Forum for Peace and Reconciliation. Yet he also had strong relations with unionists and was made a life peer on recommendation from the Ulster Unionist party in 2004 as a result of his close links to the former first minister and Nobel peace prizewinner David Trimble. A strong supporter of the peace process, Haughey had played a quiet, behind-the-scenes role in Easter week 1998 persuading the Ulster Unionists to back the Good Friday Agreement because he believed it secured the union. Once in the Lords, Haughey then switched his allegiance to the Conservative party and was a financial donor to the Tories during William Hague's leadership.
Haughey was born to Edward, who died two months before the birth, and Rose, on the Irish Republic's side of the border, in Kilcurry, north of Dundalk, Co Louth. After a traditional Roman Catholic education by the Christian Brothers in Dundalk, he went into business using his experience in farming to launch a career in veterinary medicine, and until the late 60s worked in New York as a salesman in the pharmaceutical industry. By the time he returned to the Irish border region with plans to open Norbrook, Northern Ireland was in turmoil and on the edge of incipient civil war.
Nonetheless, he kept the factory going through the darkest years of the Troubles and amassed a fortune of more than £650m while at the same time buying up properties including a six-floor house in Belgravia, central London, and Gillingham Hall, in Norfolk, from where his final, fatal helicopter flight took off, which he bought for an estimated £2.5m in 2005. Three other men died alongside him in the crash. He also owned land by Lake Victoria in Uganda.
Despite dabbling in politics, Haughey rarely gave interviews, and he resisted the temptation to float his main business on the stock exchange. In a telling – and indeed rare – remark to the Irish Independent, the peer said: "I find it difficult to work with other people. I don't know whether it's an insecurity on my part or whether I'm an autocrat or even a combination of both. But whatever it is, it has resulted in me not being able to work fruitfully with other people."
In 1972 he married Mary Gordon Young. She survives him, along with their daughter and two sons.
• Edward Haughey, Lord Ballyedmond, industrialist and politician, born 5 January 1944; died 14 March 2014