Brock had worked in Port Pirie's lead smelter, which was eventually acquired by Nyrstar, since arriving in the town in 1976.

By 21 January 2009, both the ABC's Antony Green and the state electoral office were indicating a 2-point swing against the Liberals toward Labor on 51.4 percent, but not enough to lose the seat.

[18] Such did not indicate who he would support in a minority government before he was diagnosed and hospitalised with a brain tumour and took medical leave one week after the election.

University of Adelaide Professor and political commentator Clem Macintyre said Such's situation virtually guaranteed Brock would side with Labor.

[21] A few months later, Labor achieved majority government when Nat Cook won the 2014 Fisher by-election which was triggered by the death of Such.

Despite this, Weatherill kept Brock and another independent minister Martin Hamilton-Smith in cabinet, giving the government a 26 to 21 parliamentary majority.

[24] At the election, Brock defeated incumbent member and Deputy Premier Dan van Holst Pellekaan.

[26] He said he had not expected a ministerial position, and the offer by new Premier Peter Malinauskas two days before the swearing-in ceremony came as "a heck of a shock".

He emphasised that "he was not a Labor minister, but would vote with cabinet on decisions made by it", and Malinauskas said that Brock's independent would be "maintained and utterly respected".