- For the American poet and translator, see Geoffrey Brock.
Before state politics
Brock had worked in Port Pirie's Nyrstar smelter since arriving in the town in 1976. He was first elected to the Council (at that time a City Council) in 1989, and served on numerous community committees before being elected Mayor in May 2003, defeating sitting mayor Ken Madigan by 3,297 votes to 2,173. He retired from Nyrstar in September 2007, and he and his second wife Lyn have 12 grandchildren between them.
Brock had a shock win at the 2009 Frome state by-election, defeating the Liberal candidate Terry Boylan. He had a high local profile prior to the election, having served for almost six years as the Mayor of the Port Pirie Regional Council. Independent Senator Nick Xenophon also campaigned for Brock.
On 23.6 percent of the primary vote and 51.7 percent of the two-candidate preferred vote, Brock's election was dependent on preferences from Labor, Nationals SA, and the SA Greens, the former two having placed him second on their how to vote card. His own how to vote card saw him preference the Nationals, Labor, Liberal, Green, and One Nation, in that order. The by-election was closely contested, with the result being uncertain for over a week. Initial reports suggested a slight swing to the Liberal candidate Terry Boylan on the two-party preferred count against Labor, but with Independent candidate Geoff Brock not far behind Labor. By 21 January 2009, both the ABC's Antony Green and the State Electoral Office were indicating a two percent swing against the Liberals toward Labor on 51.4 percent, but not enough to lose the seat. Liberal leader Martin Hamilton-Smith claimed victory on behalf of the party.
However, the result hinged on the performance of Brock against Labor in the competition for second place. Brock won the primary vote in the Port Pirie area and received enough preferences, ending up ahead of the Labor candidate by 30 votes. He then received enough preference votes from Labor and other candidates to achieve a two-candidate preferred vote of 51.7 percent (a majority of 665 votes) against the Liberal candidate, despite a slight improvement in the Liberal vote since the previous count.
Brock increased his primary vote to 45.2 percent and two-candidate vote to 58.8 percent at the 2014 election. The election resulted in a hung parliament with 23 Labor seats, 22 Liberal seats, and two independents. The balance of power is held by crossbench independents Brock and Bob Such. Such did not indicate who he would support in a minority government before he was hospitalised and on two months sick leave, after which Brock backed Labor. Brock accepted the portfolio offers of Minister for Regional Development and the Minister for State and Government Local Relations.
- "Shock results in local govt elections in SA". ABC Online. 13 May 2003. Retrieved 25 January 2009.
- "New mayors elected". Local Government Association of SA. 13 May 2003. Retrieved 25 January 2009.
- Pepper, Chris; Crouch, Brad; Castello, Renato; Kyriacou, Kate (25 January 2009). "Shock Frome loss rocks SA Liberals". The Advertiser. Retrieved 25 January 2009.
- "Brock claims victory in Frome by-election". ABC Online. 24 January 2009. Retrieved 25 January 2009.
- Deals put former SA premier's seat on line: The Australian 14/1/2009
- Independents unite to support Brock in bid for by-election glory: Flinders News 15/1/2009
- Greens to run open ticket in Frome: The Independent 14/1/2009
- ABC Antony Green's Frome by-election Results blog
- "Frome by-election goes down to the wire". ABC Online. 18 January 2009. Retrieved 25 January 2009.
- Green, Antony. "Frome By-election Results". ABC Online. Retrieved 25 January 2009.
- Emmerson, Russell; Pepper, Chris (18 January 2009). "Liberals confident they'll hold Outback seat of Frome". The Advertiser. Retrieved 25 January 2009. [dead link]
- "Liberals claim victory in Frome". Poll Bludger (Crikey). 21 January 2009. Retrieved 25 January 2009. This article reproduces the original Liberal press release, no longer available on the SA Liberal site.
- Frome one loss to another: Independent Weekly 30/1/2009
- Frome, a lost moment for the Libs: Independent Weekly 30/1/2009
- Pepper, Chris (25 January 2009). "Shock Frome loss rocks SA Liberals". The Advertiser. Retrieved 25 January 2009.
- Peace plea as Nationals take revenge on Liberals at polling booth: The Australian 31/1/2009
- "Independents Bob Such, Geoff Brock likely to hold balance of power as hung parliament looms". ABC.net.au. 16 March 2013.
- Labor to form minority government with support of independent Geoff Brock: ABC 23 March 2014
- Parliament Profile
- The other side of Geoff Brock: A biography by 'The Recorder' 26/2/2009
- Frome MP Geoff Brock not aligned to any party: ABC Video 3/2/2009
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