ALP 13.8%
Incumbent MP
Leon Bignell, since 2006.
Geography
Southern fringe of Adelaide and rural areas to the south of Adelaide. The seat covers the Adelaide suburbs of Aldinga, Aldinga Beach, Port Willunga, Willunga, Sellicks Beach, Tatachilla and McLarens Flat, as well as the towns of Yankalilla, Myponga, Sellicks Beach and Cape Jervis, as well as the entirety of Kangaroo Island.
History
Mawson has existed since the 1970 election. The ALP and Liberal Party have exchanged the seat back and forth, with the ALP winning the seat a majority of the time.
Two successive Labor MPs held the seat from 1970 to 1979. In 1979, the Liberal Party’s Ivar Schmidt won the seat for one term, losing in 1982.
Susan Lenehan won the seat for the ALP in 1982. She went on to serve as a minister from the late 1980s until 1993. In 1993, she attempted to move to the new seat of Reynell, but lost the race.
The Liberal Party’s Robert Brokenshire replaced Lenehan in Mawson in 1993. He went on to win re-election in 1997, and served as a minister from 1998 until the government’s defeat in 2002. Brokenshire then served as a shadow minister, until he lost his seat in 2006.
Brokenshire went on to join the Family First Party and was appointed to fill a casual vacancy in the South Australian Legislative Council in 2008. He was re-elected to the Legislative Council at the 2010 election. He held his seat until his defeat in 2018.
Labor’s Leon Bignell won Mawson in 2006 and has been re-elected four times. The seat was significantly redrawn prior to the 2018 election to expand to Kangaroo Island and the Fleurieu Peninsula, which weakened Labor’s position by almost 9%, but Bignell held on.
Bignell significantly increased his margin in 2022. Bignell was elected Speaker in early 2024, and resigned from the ALP while holding that role.
Candidates
Sitting Labor MP Leon Bignell is not running for re-election.
- Lesley Gray (Legalise Cannabis)
- Tyler Green (One Nation)
- Mike Holden (Liberal)
- Jenni Mitton (Labor)
Assessment
Mawson is a safe Labor seat.
| Candidate | Party | Votes | % | Swing |
| Leon Bignell | Labor | 12,288 | 51.2 | +15.8 |
| Amy Williams | Liberal | 6,724 | 28.0 | -6.6 |
| Jason Garrood | Greens | 2,126 | 8.9 | +0.7 |
| Jennifer Game | One Nation | 1,574 | 6.6 | +6.6 |
| Steve Campbell | Animal Justice | 574 | 2.4 | +2.4 |
| Lynton Barry | Family First | 443 | 1.8 | +1.8 |
| Peter Ieraci | Family Party | 279 | 1.2 | +1.2 |
| Informal | 745 | 3.0 |
2022 two-party-preferred result
| Candidate | Party | Votes | % | Swing |
| Leon Bignell | Labor | 15,322 | 63.8 | +13.1 |
| Amy Williams | Liberal | 8,686 | 36.2 | -13.1 |
Booths have been divided into four parts: north-east, north-west, Yankalilla and Kangaroo Island.
Labor won a majority of the two-party-preferred vote in all four areas, ranging from 56.2% in Yankalilla to 70.9% in the north-west.
The Greens came third, with a primary vote ranging from 6.4% on Kangaroo Island to 11.2% in the north-west.
| Voter group | GRN prim | ALP 2PP | Total votes | % of votes |
| North-West | 11.2 | 70.9 | 4,960 | 20.7 |
| North-East | 9.6 | 64.2 | 4,166 | 17.4 |
| Yankalilla | 7.7 | 56.2 | 2,670 | 11.1 |
| Kangaroo Island | 6.4 | 60.4 | 2,146 | 8.9 |
| Other votes | 8.2 | 62.9 | 10,066 | 41.9 |
Election results in Mawson at the 2022 South Australian state election
Toggle between two-party-preferred votes and primary votes for Labor and the Liberal Party.
Given the expected strong result for state Labor, this might be a good time for incumbent MP Leon Bignell to step down and pass the reins onto a successor.
This occurred for the WA seat of Albany, with long serving and popular MP Peter Watson stepping down in 2021 and Rebecca Stephens easily succeeding him.
Should Bignell run for re-election, he should win easily but could come under challenge by 2030 (where a more neutral environment would make it harder for Labor to win, either with him or a new candidate)
@yoh and then shed was easily defeated in march. This seat is probly easier to retain for labor then some seats
https://www.abc.net.au/news/2025-11-27/labor-mp-leon-bignell-quits-politics/106074020 – Update for this seat with sitting MP and House Speaker Leon Bignell to retire at the upcoming state election.
Mawson is a potentially difficult seat to hold for Labor being a mixed urban-rural district. But if the new MP builds up some personal vote, then they should be able to retain the seat even under more neutral conditions for future elections.
1st time Labor…Bignell won very narrowly but second time the margin was 13%… the difference was he won Kangaroo Island a conservative stro g hold. This was due to his work during the bushfire there. There is a huge personal vote here in excess of 20%