Lord Hay was a founding member of the DUP and served for many years as Chairman of his local Londonderry association, and has been an Executive member of the party for many years.

He was first elected to Londonderry City Council in 1981 and served as Deputy Lord Mayor from 1992 to 1993, and Mayor of the City from 1993 to 1994. In 1998, he was elected to the Northern Ireland Assembly and became Speaker in 2007 following the restoration of devolution. Lord Hay continues to take a keen interest in local community issues and became a Life Peer in 2014.