Quinlan is an Irish businessman prominent in the field of real estate investment and development. A former tax inspector at the Irish Revenue Commission, he formed investment syndicates of high-net worth individuals and to buy properties across the world. His principal investment vehicle was Quinlan Private, a private equity firm with offices in Dublin, London and New York. Quinlan's period of greatest prominence and success coincided with the peak of the global real estate bubble in 2004-7. In 2009, he resigned from Quinlan Private and moved to Switzerland to live in a villa on the shores of Lake Geneva owing huge sums. His loans have been transferred since to Nama (National Asset Management Agency of Ireland) which, in an effort to recoup some of the money, seized various assets, including his private collection of 16 paintings.