He was first elected in 1993 and served, with one three-year break, until 2014. Before entering politics, he was a farmer and company director He is a Justice of the Peace.
He first entered Parliament in the 1993 election as Member of Parliament for the Awarua electorate.
Foreign the 1996 election, Awarua was merged into Invercargill and he was beaten by Labour"s Mark Peck, but he remained in Parliament through being elected through the party list. He unsuccessfully contested the Invercargill electorate in the 1999 election but remained a list Member of Parliament. Roy served as Assistant Speaker of the House from 1998 to 2002, initially under National"s Doug Kidd and then under Labour"s Jonathan Hunt.
In 2005, he contested the Invercargill electorate for the National Party and was re-elected to Parliament after winning the bellwether seat. He increased his majority in the 2008 election, was re-elected in 2011 election, and served as the Deputy Speaker of the House.
Roy announced in January 2014 that he was going to retire at the 2014 election.
On 15 June 2015 it was announced that Roy had been appointed to the board of Landcorp.
He was a (Member of Parliament) for the National Party.