Quinn joined
Arthur Andersen & Co. in London and, in 1969, he returned to Dublin to head up their audit practice in Ireland until 1980. In 1980, he joined
Glen Dimplex – a small, privately owned Irish company – as deputy chairman and finance director. The company now has annual sales of $1.3 billion and employs 8,000 people in Europe and Canada. Quinn was one of two shareholders but in 2004 sold his interest back to
Martin Naughton. Quinn is also a former director of AIB Bank (1995–96), former chairman of
Allied Irish Banks Group, and half-owner of The
Merrion Hotel.
AIB Following the fraudulent trading activities at AIB's American subsidiary - AllFirst - both Quinn and the Chief Executive, Michael Buckley, offered their resignations to the board of AIB on Tuesday, March 12, 2002, but were asked to stay on by the board. ==Private business interests==