Sir Allen McClay: Philanthropist and entrepreneur whose Ulster pharmacy company thrived throughout the Troubles

Sir Allen McClay liked to describe himself as "one of the world's worst pharmacists", yet the world-leading pharmaceutical and biotech companies he created made him the most successful businessman Northern Ireland has yet produced and the most significant philanthropist the province has known.

Born the youngest of six children in Cookstown, Co Tyrone, in 1932, he attended Belfast College of Technology but said science was one of his weakest subjects. The "dramatic interest" he conceived in pharmacy at 16 he ascribed to the discovery that he would be paid five shillings a week if he was indentured for that, rather than having to pay for an apprenticeship as in most other trades or professions.

His family did not have the money to enable him to think of pursuing ambitions in the law or architecture, but one of his sisters had died of diphtheria at the age of seven and some of his most vivid childhood memories were of visiting a young girl with polio who was attached to an iron lung. Another "huge" influence was his Aunt Minnie, a local schoolteacher whose favourite saying was "the Lord will send you nuts when you have no teeth left".

So he worked hard at his pharmacy apprenticeship, qualified, and was offered a position managing a pharmacy in Co. Down. After two years he was recruited by Glaxo as a sales representative, and believed that he learnt his science and business in his 13 years visiting doctors, hospitals, clinics, chemists and vets. On the other hand he was aggrieved that he "never got an ounce of promotion". He acknowledged "altercations" with management, admitting: "I was never a great man to be subject to formalities."

In 1968 he started his own pharmaceuticals company; few imagined the enterprise, Galen, would last three months – and within a year Northern Ireland's "Troubles" began. Yet Galen survived and even prospered, growing throughout the decades of bloodshed and chaos. In 1997, a year after the ceasefire, he took the company public.

It made Galen Northern Ireland's first billion-pound company and McClay a rich man (the Sunday Times Rich List at one time estimated his wealth at around £300m). But that made little difference to his distinctive lifestyle or management methods. "I hate caviare and champagne gives me flatulence," he said. For years he drove the same Renault Safran (which, he claimed, doubled in value when he filled its tank), he did not have a reserved car park space and his offices were functional rather than lavish.

In the early days he was known for his habit of interrogating staff in the company kitchen while cooking their lunch. Some took detours if the boss was peeling spuds, but the camaraderie earned the loyalty of employees – and the boss was as dedicated to his people as they were to him.

So when it became apparent in 2001 that Galen's purchase of a US company, Warner Chilcott, meant that the board intended to focus on the US and cut up to 800 jobs in the company's home town of Craigavon, Co. Armagh, McClay was having none of it.

"The people I worked with had been my family since 1968, and now they were being scattered to the four winds", he explained. He consulted a local lawyer about buying Galen's Craigavon divisions, and was told there would be legal problems because he was Galen's non-executive chairman and on the board. McClay rang the lawyer next morning. "I've solved all the legal issues," he said. "I've resigned". The decision, he said, was "as easy as taking off dirty socks".

Inspired by a meeting with Professor Patrick Johnston from the Cancer Research Unit at Queen's University about his work using chip technology to test for colorectal cancer, Allen McClay started out anew. At 69, when most men would have retired (McClay did not like boats or too much sun, but he was a keen golfer), he decided he had "done nothing worth writing about ... I knew I'd missed something with Galen. I didn't have the involvement in hi-tech original research. That's exciting. You're opening oysters and waiting to see if you got the pearl."

He rented an empty Portakabin opposite the offices of the multi-national he had founded and in which he was still majority shareholder. He up-ended an old oil drum and got down to business on his mobile.

Soon his new company, Almac Sciences, was back in control of the Craigavon jobs. He acquired the Galen name, moved back into the Galen offices, and, quoting Aunt Minnie ("If you're going to launch big ships you have to go where the water's deep") he took his new company into America.

Almac's work covers areas such as cancer, AIDS and cardiovascular disease. "It isn't gold standard, it's platinum standard in medical terms," McClay said. It is also one of Northern Ireleand's biggest companies, with a turnover of £167m, employing 1,300 in Craigavon and another 800 in the US.

In 1997 McClay established the McClay Trust which donated £20m to Queen's University, and funded the £3.5m McClay Research Centre at the School of Pharmacy, opened in 2002.

Last year he vested his personal wealth (recently estimated at £190m) in the McClay Foundation, a charitable trust focused on cancer research. On a trip to view progress on Almac's new US headquarters in Philadelphia McClay was taken ill with cancer. He married his partner, Heather Topping, a former employee who had been at his side for many years, in hospital in Philadelphia in November.

Robin Young

Allen McClay, businessman and philanthropist: born Cookstown, Co Tyrone 21 March 1932; OBE 1994, CBE 2000, Kt 2006; married 2009 Heather Topping; died Philadelphia 12 January 2010.