Gillon's political career began when he joined the Democratic Party. In 1991, the Democratic party joined the Alliance as one of the four founding parties. In the, Gillon stood in the electorate and came third. Gillon was elected to Parliament as an Alliance list MP in the 1996 election, having been ranked in eleventh place on the party list. He was re-elected to Parliament in the 1999 election. While an MP, Gillon was a Government Whip, Deputy Chair of the Government Administration Select Committee, members of the MMP Review Committee, a member of the Privileges, Officers of Parliament, Standing Orders, Members' Services, Business, Parliamentary Services, Legislative, Cabinet and other parliamentary committees. In 2001, Gillon became leader of the Democratic Party, replacing John Wright. When the Alliance collapsed in 2002, Gillon and the Democratic Party joined Jim Anderton's breakaway party, the Progressive Coalition. In the 2002 election, Gillon was ranked third on the Progressive Coalition list, behind Jim Anderton and Matt Robson. Gillon left the Democratic Party and moved to the Progressive Coalition. Gillon became President of the Progressive Coalition until he stood down in 2007. He has served as the North Shore City Councillor and Birkenhead/Northcote Community Board member, elected to both the City Council and Community Board. Gillon is a past Chief Executive Officer for the ISEA union for teachers and past member of the Board of Directors of the state-owned enterpriseAsureQuality. Gillon has also worked as a dairy farmer, senior fire officer, and an entrepreneur in light manufacturing, printing, educational resource and publishing. As of 2017 he managed the Esplanade Hotel on Auckland's North Shore. During the 2016 Auckland elections, Gillon ran for the North Shore ward of the Auckland Council and missed out on a seat by 128 votes. He was re-elected to the Devonport-Takapuna Local Board as its Chair. He tried to win election to Auckland Council under the More for the Shore banner in the 2019 local body elections but was unsuccessful, being defeated by the two incumbent councillors.
Publishing
Gillon's published works include:
United to Protect: An Historical Account of the Auckland Fire Brigade, 1848–1985
Where There's Smoke, an exposé of insurance evasion in relation to The Fire Service
He has also contributed chapters to other works, including:
Gillon and his family have been long-term residents of the North Shore. Gillon also performs community work and is a member of the Birkenhead Licensing Trust, Northart, Birkenhead-Northcote Glenfield Community Trust and other community organisations. His daughter, Paula, is also active in Auckland local body politics; having been elected in 2001 to the North Shore City Council two weeks after reaching the required age of eighteen. Gillon has a master's degree in Public Policy and a PhD in Public Policy.
