Qualifying as a pharmacist in 1953, he went on to establish Galen in 1968, floating the multi-national business on the stock exchange in 1997. Retiring as Galen's President in 2001, he was back in business less than six months later with a series of acquisitions that created the Almac Group.
Throughout all of this, the Cookstown-born entrepreneur has maintained a business presence in Craigavon, and helped keep Northern Ireland on the international pharmaceutical and biotech map. Paying tribute, staff spoke warmly of the boss who ate alongside them in the firm's canteen. He seemed to have earned the intense loyalty of his staff and colleagues.
Through the McClay Foundation (and before that, the McClay Trust), he also invested in local education - with multi-million pound donations QUB for Chemistry and Pharmacy education and scholarships, a research centre over at the City Hospital, and a £10 million contribution to the new central library.
Hearing the news reminded me of a television programme a year or two back that profiled this humble and generous figure. And as if by magic, the Thinking Big programme that local indie Below The Radar made for BBC NI has been put online. Well worth a watch.
Sir Allen McClay - one of Northern Ireland's giants.
Update - the programme will be shown on BBC One NI after the Ten O'Clock News at 22:35 on Tuesday 19 January.