Michael McGimpsey (53) and his brother, Chris, came to public notice in the Republic in the early 1980s when they went to Dublin to present the unionist case to the New Ireland Forum.
Four years ago they returned to Dublin to challenge Articles Two and Three of the Constitution but the case was eventually dismissed by the Supreme Court.
The McGimpseys come from a politically-active family in Newtownards, Co Down. Michael studied English, history and economics in TCD in the 1960s. He returned to Newtownards to work in his father's construction firm and opened a do-it-yourself business as a sideline.
He has always been on the liberal wing of the Ulster Unionist Party.