Trimble began his career as a Professor of Law at The Queen's University of Belfast in the 1970s, during which time he began to get involved with the paramilitary-linked Vanguard Progressive Unionist Party. He was elected to the Northern Ireland Constitutional Convention in 1975, and joined the UUP in 1978 after the VPUP disbanded. Remaining at Queen's University, he continued his academic career until being elected as the MP for Upper Bann in 1990. In 1995 he was unexpectedly elected as the leader of the UUP. He was instrumental in the negotiations that led to the Good Friday Agreement in 1998, and (along with John Hume) won the Nobel Peace Prize that year for his efforts. He was later elected to become the first First Minister of Northern Ireland, although his tenure was turbulent and frequently interrupted by disagreements over the timetable for Provisional Irish Republican Army decommissioning.