Sir Allen and Bertie Robinson shared many investments together including the Connors Chemists chain and Galen Research.
Sir Allen left Galen, which produces contraceptives and hormone replacement therapy drugs, in 2001, having become unhappy with the company's direction after its London Stock Exchange flotation in 1997.
[5][8] In 1973, McClay and Bertie Robinson invested in Connors Chemists, a pharmacy in Warrenpoint, which developed into a chain of branches across the UK managed by his brother Howard, and was sold to The Boots Company in 1998.
[8] In recognition the university commissioned two portraits of McClay by local artist Ian Cumberland, one of which was gifted to his wife the other is on display in the library.
McClay was reported by the 2009 Sunday Times Rich List to be Northern Ireland's sixth richest person, with his wealth estimated at £190 million.