Holbrook by-election, 2015

A by-election was held for the Craftian House of Representatives seat of Holbrook on Saturday 28 March 2015. It was triggered by the resignation of sitting member Brian Heath of the Craftian Conservative Party, citing health concerns and dissatisfaction with his position as a backbencher, following a party leadership spill in 2014 resulting in him losing the leadership to James Traves. Heath had held the seat since a by-election in 1996.

The by-election was narrowly won by John Mayweather for the Craftian Reform Party, in the shock result in a normally ultra-safe Conservative seat. The Conservatives suffered a swing of 21.32% in the two-party-preferred count and their primary vote was cut by more than half. The by-election served as a prelude to the election of the Reform Party into government the following year.

A total of 16 candidates nominated to contest the by-election, including all major parties. This was up from just four candidates at the 2013 election.

Seat overview
Holbrook was normally an ultra-safe seat for the Conservative Party and its predecessors, with the last time a left-leaning party winning the seat in 1953. Brian Heath, the sitting member, had held the seat since 1996, and was immensely popular in the electorate, building up a strong personal vote that allowed Holbrook to become one of the safest seats in parliament, with a TPP result of 71.38% for the Conservatives in the 2013 election, in which Heath was party leader. The CCP failed to form government following the election, and Heath's hold on the leadership began to falter. By 2014, his popularity had declined significantly and was defeated in a leadership spill by James Traves, a former leader. Heath moved to the backbench and originally planned to stay in parliament until the following election, but in January 2015 announced his resignation, thus facilitating the need for this by-election.

The seat was seen as vulnerable to being taken by a resurgent National United Party or possibly the Reform Party, as both parties had seen an increase in the polls while the Conservatives continued to decline. However, most political commentators predicted that the Conservative Party would retain Holbrook, due to the electorate's status as a longstanding bastion for the party.

Results
The Conservative Party suffered a heavy swing against it, with its primary vote falling from 69.49 percent to 31.17 percent. The seat was extremely narrowly won by Reform, by just 26 votes, a 0.12 percent margin.