Career
Gardiner was elected to Lurgan Borough Council (now Craigavon Borough Council) in 1963 and held office of Mayor in that borough in 1968. He was Mayor of Craigavon 1982/3, 1988/9 and 2000/1. He was elected to the Northern Ireland Forum and was party whip in the same in 1996-1998.
Gardiner was elected to the Assembly in 2003.
He serves on the Environmental, Leisure Services and Public Services Liaison Committees and is UUP Spokesperson on Environment. As the oldest Northern Ireland Assembly member, Gardiner also serves as Father of the House, a role which includes presiding over the election of a new Speaker of the Assembly.
He is a former High Sheriff for County Armagh and was appointed as a Justice of the Peace.