In August 1981, he was the Alliance candidate for the second Fermanagh and South Tyrone by-election. The following year under the redistribution and expansion of Northern Ireland's constituencies his local political base became part of the new Lagan Valley constituency which he has contested in the Alliance interest in all elections since 1983 apart from the 1986 by-election called in protest against the Anglo-Irish Agreement when the local Alliance branch declined to contest the seat as they believed the by-election was a political stunt.
Close also held several positions in the Alliance, including serving as Chair between 1981 and 1982 and as Deputy Leader from 1991 until 2001. He was often a member of the key Alliance delegations in successive talks about the future of the province, culminating in the Belfast Agreement of 1998.
In the 1996 elections for the Northern Ireland Forum, Close stood at the head of the Alliance's list for Lagan Valley but the party failed to secure enough votes to win one of the local seats. Close was also included on the province-wide list, and as the most senior Alliance member to not be elected locally he won one of Alliance's two seats. In the 1998 election for the new Northern Ireland Assembly he topped the poll in Lagan Valley and gained a further personal triumph in the 2001 general election when he had the highest vote share of any Alliance candidate.
In June 2001, he resigned as Deputy Leader of the party,[3] citing differences with the leadership of Seán Neeson. Close has remained a member of the Assembly and successfully held his seat in the 2003 Assembly election.
In July 2005, Mr Close proposed that the Lisburn Council deny gay couples access to the council's designated wedding facility if they were seeking a civil partnership under the Civil Partnership Act 2004. The council adopted his recommendation, to the great annoyance of many liberal campaigners. This ran against Alliance policy, which had been strongly supportive of the introduction of civil partnership laws, and he was publicly criticised by other senior party members.[2]
In November 2006, Close announced that he was retiring from politics[2] In the 2007 election he was succeeded as Alliance Party Lagan Valley Assembly representative by the then Mayor of Lisburn, Councillor Trevor Lunn.[4]
